(loud explosion) NARRATOR: 70 years ago, the nuclear bomb altered our reality forever.

RICHARD RHODES: For the first time in human history, we now were capable of our own destruction as a species.

NARRATOR: The bomb affects everything.

ELAINE TYLER MAY: It was the opening shot of the Cold War.

LAURA McENANEY: All U.S. citizens are now going to have to be on high alert.

RADIO ANNOUNCER: This is a radio alert.

TIM NATFALI: The bomb produces some of the worst psychological tension ever in world history.

NARRATOR: An international arms race, confrontations and close calls.

Politics, culture, even sex.

MAY: There was a kind of thrilling excitement about it.

Fire.

NARRATOR: Entire industries were created to build it.

ANNOUNCER: This incredible energy opens limitless horizons.

NARRATOR: New cameras, film stocks, and techniques devised to photograph it.

Now, thanks to state of the art restoration of original film masters, we can see the incredible power of this device in a new way.

A technology that has changed human existence forever.

ROBERT NORRIS: The bomb has receded in the public's imagination, but it's still there.

NARRATOR: We still live in its shadow.

WILLIAM PERRY: Everybody is affected by it.

There's no place to hide.

MARTIN SHERWIN: It is an environmental issue, it's a political issue.

It's a moral issue.

It is the most important issue that we face.

NARRATOR: The Bomb.

ANNOUNCER: The Bomb was made possible in part by contributionsIt first appeared in the New Mexico desert... A place the Spanish called Jornada del muerto-- "journey of the dead."

Here, miles and miles from anywhere, the Bomb came to life.

The exact spot is inaccessible, hidden inside a 3,000 square mile weapons range.

But for a few hours, once every year, it's opened to the public.

Thank you.

Thank you.

Hope you like Mike Tyson.

(indistinct chatter) NARRATOR: They come from all over, like pilgrims to a shrine to see and stand in the spot where the nuclear age began.

Where the modern era started.

It's probably what it is: a turning point.

We actually are at ground zero, where it actually happened.

Well, it's world history, too.

It changed-- it changed everything.

NARRATOR: The bomb that was tested here 70 years ago turned night into day, and set the world on a new and dangerous path.

It was a beginning that would lead to over a thousand nuclear explosions through five decades.

Test after test in desert landscapes... ...on tiny islands.

A Cold War that brought the world to the brink and produced an enormous stockpile of bombs, most of which could destroy in one instant a city, and much more.

60,000 nuclear weapons, between the United States and the Soviet Union.

NAFTALI: If something should go wrong, the consequences would be catastrophic, not simply for one nation or another, but for mankind.

NARRATOR: No less than the discovery of fire, the bomb marks a dividing line between all that came before, and everything that follows.

PERRY: Nuclear war would entail the end of civilization.

This was a millennial change in human affairs.

Everyone was at risk.

NARRATOR: The force that first appeared on this spot-- a power greater than we can imagine-- where did it come from?

How did it all start?

SHERWIN: The understanding of how the world worked was being revolutionized.

And in 1938, in Germany-- and it's important to emphasize in Germany-- the greatest revolution of all occurred.

NARRATOR: In Berlin, two German chemists, Otto Hahn and Fritz Strassman, discover that bombarding uranium with neutrons creates a different substance: barium.

They have no idea why.

But a friend, physicist Lise Meitner, suddenly realizes they have split the nucleus of the uranium atom, what she calls "fission".

Meitner publishes her conclusion in the scientific journal Na ture.

The news begins spreading through the international physics community.

SHERWIN: The implications of that were obvious to physicists all over the world.

Out of a little bit of material, it can produce an enormous amount of energy.

NARRATOR: The timing could not be worse.

Nazi Germany is on the rise.

Adolph Hitler is about to start World War II.

(gunshots and explosions) As physicists around the world digest Lise Meitner's news, they quickly realize this discovery-- nuclear fission-- could determine the outcome of the war.

LOEBER: Uranium... NORRIS: ...can be fissioned... ...when hit with a neutron... ...producing... ...a tremendous amount of energy... ...a lot of energy... LOEBER: ...per Einstein's equation... RHODES: ...E=MC squared... NORRIS: ...every physicist knew... ...all over the world... ...an atomic bomb could be built... ...by the Nazis.

RHODES: After all, the discovery had been made in Germany.

Germany had very good physicists.

Maybe Hitler's building the bomb.

The threat of Germany getting a bomb first is so unthinkable.

NORRIS: Hey, we're in a race with the Germans, perhaps.

NARRATOR: But so far the race is only in the scientists' minds.

No one else understands the danger of a bomb that doesn't yet exist.

Physicist Leo Szilard is convinced the only way to stop Hitler is to get the bomb first.

Szilard dictates a letter, a warning about the threat of a Nazi atomic bomb.

NORRIS: And he thought that the best strategy would be to get Albert Einstein, the most famous scientist in the world, to sign a letter to the president, Franklin Roosevelt, and get things moving.

NARRATOR: Szilard's letter and Einstein's fame do the trick.

President Franklin Roosevelt authorizes a project to research uranium.

Two years later, the Japanese attack Pearl Harbor... Hitler declares war on the U.S. America is fighting two wars: against Germany in Europe, Japan in the Pacific.

Suddenly, Roosevelt's uranium research project is critically important.

What began as scientific inquiry is about to become a crash program to build a bomb.

The bomb had its roots in many places, all of them managed by the U.S. Army Corps of Engineers.

In this building, on Broadway in New York City, the engineers set up an office.

On the 18th floor, the largest government scientific project in history begins to take shape.

To keep its real purpose secret, the project is named after the engineer district where it's located: Manhattan.

Ultimately, over half a million people will contribute to the Manhattan Project.

They'll be led by this man: Leslie Richard Groves, Army engineer.

Groves has been in charge of building the Pentagon, and internment camps for Japanese-Americans.

Now he's itching for the next step in his career: an overseas combat assignment.

Then Groves gets a surprise update from his boss.

NORRIS: I have a project for you.

And Groves realizes what it is.

Oh no, not that thing.

No...

He's ready to go overseas, and he's very disappointed.

NARRATOR: Developing an imaginary bomb based on invisible particles that will probably never work seems like a career dead end.

But, hey, you do what you're told.

You do what you're told, and you do it to the best of your ability, and he put his foot on the accelerator and never let up.

NARRATOR: But first he negotiates a raise.

NORRIS: He says I'm gonna have to be a general.

I mean these scientists aren't going to respect me if I'm just a colonel.

NARRATOR: Now he gets to work.

Friday, day one: purchase 1,200 tons of uranium ore. Saturday: negotiate special top priority rating for the project.

Monday: meet with presidential science adviser Vannevar Bush.

Wednesday: go to Tennessee, buy 56,000 acres of land for factories.

Next, visit universities and meet scientists.

Columbia: Harold Urey.

University of Chicago: Arthur Compton.

Berkeley, California: Ernest Lawrence.

Back to Washington.

Groves has put in motion what will become a vast industrial complex in less than two months.

There's only one thing missing: the bomb itself.

It will be years before there's nuclear fuel ready.

The uranium is produced one tiny particle at a time.

But when that fuel is ready, Groves will need a design for a bomb that works.

And for that, he needs scientists.

He's been meeting plenty of them at Columbia, Chicago, Berkeley.

No question they're smart, but they just rub him the wrong way.

NORRIS: He's a military man, so we've got a clash of cultures here.

RHODES: Groves was a very smart man.

And knew a lot about a lot of things.

But he didn't know much about physics.

He also had a pretty thin skin about people looking down on him who had PhDs, which he didn't have.

Eggheads.

He thinks that these guys are up in the clouds.

They're not very practical, their politics are, for the most part, suspect.

They talk too much, what about security here, this is gonna be a big secret here, they're blabbing all over the place amongst themselves.

They're gonna have to be put in shape.

NARRATOR: Groves needs a scientist he can work with-- someone who can turn theories into a working bomb, and run a lab, and manage a team of the most brilliant and cantankerous minds ever assembled in one place.

RHODES: Against the advice of most of the senior physicists in America, he chose Robert Oppenheimer.

Oppenheimer?

Oppenheimer ran graduate seminars of 15 people.

That was it.

He couldn't run a hamburger stand.

I mean, he had no administrative record.

Groves' security people were totally against Oppenheimer.

They were appalled.

His wife's a communist, his brother's a communist, his sister-in-law's a communist.

NARRATOR: And yet the no-nonsense general senses something in this brilliant dreamer that strikes a chord.

RHODES: Oppenheimer was very good at explaining things.

And Oppenheimer explained things so beautifully and so respectfully to General Groves that Groves just was dazzled and decided this is my man.

SHERWIN: It was a brilliant decision, and insightful.

Oppenheimer understood better than any of the others what needed to be done.

NORRIS: And Oppenheimer saw in Groves something absolutely essential, which was Groves's ability to get Oppenheimer anything he wanted-- any person, any resources, anything.

NARRATOR: General Leslie Groves and Dr. Robert Oppenheimer-- complete opposites, yet each in his own way a virtuoso-- together are made for this moment.

NORRIS: The two of them were bound together and both saw in each other what I call their route to immortality.

NARRATOR: It's 1942.

Groves has his lead scientist; now he needs a special kind of uranium-- U-235-- the only substance that can make an atomic explosion.

Natural uranium, U-238, won't work.

And that's a problem.

LOEBER: The uranium that you dig out of the ground has only about seven-tenths of 1% U-235.

So we then had to figure out a way to separate U-235 from U-238.

You can't do it chemically 'cause it's all uranium.

NARRATOR: Groves builds a huge complex at Oak Ridge, Tennessee, to produce U-235.

But it's agonizingly slow.

HOPKINS: Getting U-235 is not difficult in tiny quantities, but since you have to get them one atom at a time, it is an enormous task to do that.

NARRATOR: Just one bomb will need pounds of the stuff.

Getting it one atom at a time will take years.

But chemist Glenn Seaborg finds another option: plutonium.

It can be produced faster than uranium in a nuclear reactor.

So Groves builds another complex: reactors at Hanford, Washington, to produce plutonium.

But all this will take time.

And both wars are going badly.

In the Pacific, the Japanese capture the Philippines.

They force 60,000 weak and starving POWs to walk 60 miles with little food or water-- the Bataan Death March.

LESTER TENNEY: If you stopped you were killed.

If you just couldn't take another step forward you died.

And how did they kill you?

Either bayoneted you to death, shot you, or decapitated you.

Depending on how they felt at that moment.

(gunfire and explosions) NARRATOR: The war with Germany is just as bad.

German U-boats are creating havoc in the Atlantic.

Hitler's armies occupy Europe, North Africa, and are hammering the Soviet Union.

And no one knows how close the Nazis are to an atomic bomb.

Groves is of course consumed by this question of what the Germans are up to.

NARRATOR: The Nazis are already committing unspeakable atrocities.

If Adolph Hitler gets the bomb, he will be unstoppable.

The bomb came out of the minds of men.

To create it, they would need isolation, freedom from distraction, and utmost secrecy.

Here, deep in the Jemez Mountains, they could think their thoughts, work numbers, follow the equations.

Los Alamos, New Mexico, where the scientists worked, was created by and for the bomb.

Today, only a few traces of its beginnings remain: an old mess hall... an Army barracks... Robert Oppenheimer's house...

The main lodge of what was once a private boys' school.

In 1942, Oppenheimer tells Groves this is the perfect place for a secret laboratory.

RHODES: Up on a mesa in the middle of a national forest, with only one telephone line to the outside world.

It's isolated, we'll keep these scientists away from what they're used to, and we can keep our eye on them.

So they closed the school, boom, and we can get going right away.

NARRATOR: Now Oppenheimer must convince some of the best science talent in America to move to the middle of nowhere, and live behind barbed wire for the indefinite future.

HOPKINS: They needed a good salesman to encourage these people to come to Los Alamos.

And Oppenheimer was very good at that.

NARRATOR: Eventually, thousands will be recruited to work on the bomb.

Hal Behl was an aeronautical engineer.

Lilli Hornig and her husband Don were scientists.

For all of them, joining the project began with a mysterious cryptic conversation.

HAL BEHL: Here's this major sitting behind a desk and he said, "I have a very elite job for you, but we only take volunteers."

I said, "Well, tell me about it."

He said, "I can't."

LILLI HORNIG: Don was asked, "How would you like another job?"

Don said "Well, you have to tell me a little more.

And he said "Well, I can't."

I said, "Tell me where I would be."

He says, "I can't."

Which direction in the country?

North, south, west?

"No, I can't tell you any of that."

I said, "Tell me what I'd be doing."

He said, "I can't."

I said, "You think I am going to volunteer you're out of your cotton- picking mind!"

I'm not going to risk my future on something I know absolutely nothing about, that's ridiculous!

So he said, "Hornig, you know those posters in the post office and Uncle Sam is pointing his finger at you?

Don thought that was very corny.

But we got the message.

So the next day I was on my way to Oak Ridge, Tennessee.

NARRATOR: Yet even in the midst of a national emergency, some assets are ignored.

SHERWIN: The women at Los Alamos ran the schools, the libraries, they did a lot of the calculations, but this was a male environment.

NARRATOR: Some women do work as typists and machine operators.

But of more 400 scientists at Los Alamos, less than ten are women.

Lilli Hornig is one.

HORNIG: They said, "How fast do you type?"

And I said, "I don't type."

And they said, "What makes you think you can get a job?"

I said, "I'm a chemist with a master's degree and a year of work experience."

And eventually they turned up a job in the chemistry division.

So they took some women, but they made it very clear that we were not top drawer.

NARRATOR: The first lesson everyone learns is secrecy.

Officially, Los Alamos doesn't exist; it's called "Site Y," or "the Hill."

The bomb is referred to only as "the Gadget."

You only need to know enough to do your job, and no more.

And don't be inquisitive about anything more.

ROGER RASMUSSEN: Everything was hush hush, go where you're told, and there was no preliminary information given to me.

They knew exactly who I was and why I was there.

And that was better than I knew.

JACK AEBY: I knew very little about the project.

I just picked up rumors about they're building balloons up there, submarines.

BEHL: You did not talk about bombs, atoms, uranium.

You just didn't say that.

My wife didn't know what we were doing.

NARRATOR: Oak Ridge, Tennessee, where uranium is produced, has been created nearly overnight.

BEHL: This was a town that one year before had just been a farm, and suddenly was a large city with 70,000 people, houses, streets.

NARRATOR: Los Alamos, New Mexico, is far more remote, and much less developed.

One of the scientists here, Hugh Bradner, has a movie camera.

The Bradner home movies offer a rare glimpse of life at Los Alamos.

The films are remarkable because they exist at all-- a look inside the most secret facility in the world, hidden deep in the remote West.

NORRIS: Many of these people had come from, you know, urban academic places.

And here they were living a rather primitive life.

SHERWIN: The living conditions were rough western.

You could turn on the water tap and worms were as likely as water to come out.

There was mud during the rainy season.

On the other hand, there were parties.

And Oppenheimer was a great lab leader.

And the punch was spiked with 100% lab alcohol, so it became exciting.

NARRATOR: Their average age is 25.

And they know their work may be the only thing that can prevent a Nazi atomic bomb.

HORNIG: I came to this country at the age of 12 from Hitler Germany.

And my motivation was very much tied to that.

NORRIS: All of them were told that they could shorten the war through their efforts, and that was enough to know at the time.

NARRATOR: By spring 1944, they have a design.

It resembles a gun.

Two chunks of nuclear fuel will be slammed together, creating a critical mass and a nuclear explosion.

It's simple, but there's not enough fuel to test it.

Uranium production is so slow it will take years to make enough for just one bomb.

Since plutonium can be produced faster, it is the key to making multiple bombs.

The success of the entire project depends on making plutonium work.

But when physicist Emilio Segre gets the first tiny sample of plutonium from Hanford, he makes a devastating discovery: a plutonium gun bomb will melt, not explode.

The gun-type plutonium bomb will not work.

RHODES: It was a disaster.

There was just enough uranium for one gun bomb.

If you couldn't use plutonium, there would only be one bomb.

Maybe this whole $350 million is going to go for naught because plutonium won't work.

RHODES: Oppenheimer really considered resigning from Los Alamos at that point.

NARRATOR: It's a dead end.

Los Alamos scraps the plutonium gun design and starts over.

After years of work they can only count on one uranium bomb.

It's summer, 1944.

The Allies have invaded France, but the outcome is still in doubt.

Nazi scientists are introducing frightening new weapons: the world's first jet fighter, a cruise missile, and a supersonic rocket.

They could be close to an atomic bomb.

HORNIG: We knew they were working on it, but we didn't know how far along they were.

The war could be lost if Germany got it first.

NARRATOR: In Los Alamos they've got a new approach-- a possible way to use plutonium: implosion.

Usually an explosion is outward, this time they're gonna push a ball of plutonium and compress it.

NARRATOR: Taking a ball of plutonium and using explosives to compress it might be impossible, but it's their only hope.

That was the greatest problem at Los Alamos: how to make plutonium work.

They reorganize the laboratory and there's a crash program for implosion.

NARRATOR: Chemist George Kistiakowsky from Harvard is brought in to work the problem.

Kistiakowsky will spend the rest of 1944 and beyond experimenting, desperately trying to make implosion work.

As complex and daunting as implosion is, Kistiakowsky and his small team will not be nearly enough.

They turn to the British, who send some of their scientists to Los Alamos.

NORRIS: Groves wanted all of them vetted for possible security infractions.

And the British said, "No, no, they're okay, we took care of them."

NARRATOR: Among the new arrivals is a quiet and strange refugee from Germany.

His name is Klaus Fuchs.

HORNIG: He was a very good physicist.

He made interesting suggestions, very cooperative.

But sort of an odd guy, and he made me uncomfortable.

NARRATOR: Although no one seems aware of it, besides being brilliant, and odd, Klaus Fuchs is a dedicated communist.

In a few short years, his presence at Los Alamos will come to haunt Groves and Oppenheimer.

By early 1945, the war in Europe is in its final months.

Nazi Germany is being squeezed between Americans, British, and French on the west, and Soviets on the east.

In Los Alamos, the design for the uranium gun bomb is complete.

All that's missing is the uranium.

There should be enough for one bomb by summer.

As for a plutonium bomb, they're still working on implosion.

Then, in April, tragedy.

RADIO ANNOUNCER: When he heard that his chief was dead, his simple humanity expressed itself in these words to Mrs. Roosevelt, "What can I do to help?"

NARRATOR: Now, ultimate authority over the bomb falls to Harry Truman.

My duties and responsibilities are clear.

I have assumed them.

NARRATOR: But there is one enormous responsibility that's not at all clear-- incredibly, Truman has never even heard of the bomb.

He's got this responsibility that he really didn't know about because Franklin Roosevelt didn't tell him.

SHERWIN: He had been the vice president for 82 days.

He had met once with Roosevelt, essentially for a picture.

Oh, by the way here, you're in charge of a project that could end human civilization, thank you very much.

NARRATOR: In May, Germany surrenders, the war in Europe is over.

Hitler, and the fear of a Nazi atomic bomb-- the very things that gave birth to the whole project-- are gone.

But in the Pacific, the war against Japan is still raging.

RHODES: The job wasn't done.

I was a boy of seven that spring of 1945.

And I remember vividly there were still young men being killed every day.

NARRATOR: The race may have been inspired by fear of Germany, but Japan is now the only enemy, and thus target for the bomb.

The very first bomb was called "the Gadget."

After three years and $2 billion, this is it: a six-foot sphere filled with batteries, electronics, explosives, covered with cables to set it off, and measure what happens.

At its center, a grapefruit-sized ball of plutonium-- the core.

If this thing works, the world will never be the same.

Everything comes down to a test in the New Mexico desert, code-named Trinity.

It is July 1945.

They've been preparing for months, putting in roads, shelters and bunkers, miles of cable.

It's the biggest science experiment in history.

If it works, they'll set off the world's first atomic explosion.

No one has any idea what that will be like.

They need to measure, record, photograph everything.

Radiation levels, shock waves, temperatures-- all unknown, all must be documented.

Thousands of miles away in Potsdam, Germany, President Harry Truman is negotiating with Stalin.

Does he have an atomic card in his hand?

It all depends on the Trinity test.

Back in New Mexico, George Kistiakowsky has discovered a problem.

RHODES: It looked as if the bomb might be a dud.

Since they had poured the explosive and it was hot when it was poured, there was the possibility there would be bubbles in there.

So Kistiakowsky decided he had to fill those bubbles with liquid explosive.

NARRATOR: Now Kistiakowsky must drill holes in the explosive, and carefully fill each bubble.

The outcome of the test depends on his fix, and there's no way to know if it will work.

There was a test on July 14, a full-up explosive test that went really bad, which then made them worry even a little bit more.

NARRATOR: They are out of time.

All they can do is press on, and hope.

They'll hoist the bomb to the top of a 100-foot steel tower.

They pile mattresses under it just in case.

Thousands of people, years of work are on the line.

The last crucial piece, the grapefruit size plutonium core-- a $350 million box-- is delivered by car from Los Alamos.

In Potsdam, Truman waits; the test is scheduled for tonight.

(thunderclap) NORRIS: It begins to rain and we're going to have to postpone this thing.

So there's great nervousness.

Most everybody really had a knot in their gut about all the electronic connections.

There's a zillion things could go wrong.

NARRATOR: The weather looks bad, but Groves refuses to give in.

NORRIS: And Groves becomes his own weatherman here and decides we're gonna have this test at 5:30.

It looks as though it might clear just enough to get the test in.

Dawn was just beginning to break.

We heard the countdown.

MAN: Ten... NARRATOR: It is July 16, 1945.

Three years, hundreds of thousands of people, the futures of Groves and Oppenheimer.

NORRIS: There's careers involved, there's $2 billion spent.

NARRATOR: Unproven science, a president waiting, a chance to end the worst war in history-- will it work?

The world will never be the same.

No one who was there will ever forget it.

RASMUSSEN: I couldn't believe that I would see it when I had my eyes closed!

HORNIG: It was the most incredible sight I've ever seen in my life.

It was a brilliant white yellow to start with, and developed reds and orange and purple and blue.

RASMUSSEN: I was just standing there with my mouth open.

NARRATOR: Engineer Jack Aeby has brought his camera.

I snapped the shutter wide open.

NARRATOR: Jack Aeby's picture is the only properly exposed color still photo from that night.

A new age has begun; the bomb is about to change everything.

I have to admit I didn't feel much of anything except a great joy that it was a success.

It was really later that we all began to think more about it.

NORRIS: The thing worked.

And there is plutonium flowing from the Hanford reactors to Los Alamos.

NARRATOR: Groves now knows they can make implosion bombs as fast as plutonium is produced.

In Potsdam, Truman gets the news.

NORRIS: What to do about the Russians here?

Should we tell them, what's gonna happen after the war?

NARRATOR: Truman tells Stalin the U.S. has a powerful new weapon; Stalin barely reacts because he already knows.

Klaus Fuchs has been telling the Soviets all about the bomb.

SVETLANA SAVRANSKAYA: Stalin and the people closest to him were very well informed about the progress of Manhattan Project and that's partly why at Potsdam, Stalin kind of just looks at them and doesn't say much.

NARRATOR: Back in the U.S., now that the atomic bomb is a reality, some scientists are having misgivings about using it.

Leo Szilard, who warned of a Nazi bomb, drafts a petition to the president, urging him to consider the moral consequences.

Offhand I'd have to say the scientists were probably about evenly split, for and against.

NARRATOR: Scientists also worry that using nuclear weapons now will put the U.S. in danger after the war by encouraging Stalin to pursue the bomb.

They thought if they are used, they are likely to precipitate a nuclear arms race with the Soviets.

NARRATOR: Some scientists urge a demonstration of the bomb, to give the Japanese a chance to surrender.

But to the Japanese, surrender does not seem to be an option.

They send kamikazes-- suicide pilots-- against U.S. ships.

In battle after battle, their soldiers kill themselves rather than be captured.

The U.S. is now firebombing their cities.

100,000 Japanese die in one night in Tokyo alone.

Their war is hopeless, yet they still refuse to surrender.

The next step seems unavoidable: invade Japan itself.

Thousands of Americans, and perhaps millions of Japanese will likely die.

For Harry Truman, the bomb seems by far the lesser evil.

NORRIS: "I may be faced with an actual land invasion of Japan.

"So if there's anything that can shorten the war before that, and prevent it, I'm for it."

NARRATOR: On July 26, the Japanese are given an ultimatum: surrender unconditionally or face destruction.

NAFTALI: The Japanese were not interested in unconditional surrender.

They wanted their emperor to remain in power.

They wanted to oversee their own war crimes trials.

They did not want U.S. occupation of the home islands.

NARRATOR: The Japanese reject the ultimatum.

Now all the pieces fall into alignment.

Japanese leaders who cannot bring themselves to stop, a massive science project that has spent $2 billion racing to create the bomb, a president facing a horrific battle who suddenly sees an alternative.

What happens next-- dropping two atomic bombs on Japan in August 1945-- will become one of the most controversial decisions in American history.

70 years later, remarkably, evidence suggests the president never actually gave this order.

Now that it's ready, it may be harder to stop the bomb than to let it go.

NORRIS: There is a question about whether or not Truman ever really authorized the use of the bomb.

And it's my argument that he never did, that there was so much momentum built up, that Truman, new to the job, decides not to interfere with ongoing plans.

NARRATOR: On Tinian Island in the Pacific, the uranium gun bomb, nicknamed "Little Boy", is ready.

It's never been tested, but it's so simple that they are sure it will work.

The bomb is loaded into the B-29 Enola Gay.

A few hours before dawn on August 6, the plane takes off.

It flies 1,500 miles through the night.

At 8:15 a.m., over Hiroshima, it drops the bomb.

Now the bomb controls its own destiny.

When it's 1,900 feet from the ground, it explodes.

A fireball a quarter-mile across reaches 10,000 degrees.

Anything close to the center is vaporized.

Then a shock wave explodes buildings, knocking down anything in its path.

Almost everything within one mile is totally destroyed.

Only a few concrete structures remain.

Where something, or someone, absorbed the heat, a shadow is left behind.

At least 80,000 people die.

Other bombings have killed more people.

What's new about Hiroshima is how easy it was: one plane, one bomb.

And still, even after this, the Japanese will not surrender.

LYNN EDEN: The shock of the first bomb didn't quite do it, actually.

They couldn't even at first accept that Hiroshima had been bombed.

NARRATOR: The Japanese have their own plan to end the war.

Behind the scenes, they have been secretly talking to the Soviets, hoping the Russians will broker a deal with the U.S.-- a conditional surrender.

But two days later, the Soviet Union declares war on Japan.

Now the brokered conditional deal the Japanese hoped for is dead.

But there's still no sign of surrender.

EDEN: The level of resistance in the Japanese government was very, very difficult to understand.

It was so great.

NARRATOR: On Tinian, crews are preparing the next bomb-- nicknamed "Fat Man"-- as President Truman addresses the nation.

TRUMAN: If they do not now accept our terms, they may expect a rain of ruin from the air the like of which has never been seen on this earth.

NARRATOR: On August 9, a B-29 carrying the Fat Man bomb takes off.

The target is Kokura.

But Kokura is obscured by clouds.

So the plane heads for the backup target.

Because it happens to be cloudy, thousands of fortunate people are spared.

Others will die in their place.

The second city hit by an atomic bomb will not be Kokura but Nagasaki.

(explosion) Nearby, in POW camp 17, Lester Tenney sees the explosion.

We saw this tremendous cloud rise.

And it was the most unusual thing.

It seemed to have a pedestal.

And we had no idea what it was.

NARRATOR: Up to 70,000 people are dead.

Even now, after the Soviet invasion and two bombs, Japanese leaders still cannot agree about surrender.

PERRY: The Russians invade them, they still did not surrender.

The second bomb was dropped and then the emperor decided to surrender.

Even then the Japanese army did not want to.

Nothing speaks well for the Japanese.

Nothing.

The emperor and his advisors were callously uninterested in the lives of their citizens that were being lost.

They just did not care about how their people were suffering.

NARRATOR: While the Japanese leaders try to make up their minds, Groves is planning more atomic attacks.

NORRIS: The orders for the bomb are to keep using them as made ready.

That very important phrase.

So, the bomb after Nagasaki, if necessary, and a bomb after that if necessary, and a bomb after that if necessary.

NARRATOR: They will drop atomic bombs as fast as they are built-- three or four a month.

NORRIS: And finally, Truman said enough.

No more until the president authorizes them.

NARRATOR: Finally, the day after Nagasaki, Japan agrees to surrender, on one condition: they keep their emperor.

TRUMAN: I have received this afternoon the unconditional surrender of Japan.

NARRATOR: Truman agrees, though he calls it "unconditional."

That was Japan's hope, was to surrender conditionally, to have some say in how it would happen.

NARRATOR: In POW Camp 17, the prisoners sense something's up, but they don't know what.

Lester Tenney tries a daring experiment: speak to a guard without bowing.

TENNEY: Now if you saw a Japanese guard two blocks away, you better stop, turn to him and bow.

Or you're beaten.

And so I went outside and saw the Japanese guard right out there.

And I just walked up to him, and in my best Japanese I just said: Konnichiwa, tomodachi!

And I never did stop and bow.

And he stood at attention.

And within a matter of five or six seconds he bowed to me.

He bowed to me!

The war is over!

The war was over, period.

Just exactly like that.

NARRATOR: On September 2, 1945, Japan signs the surrender documents.

World War II is over.

RHODES: The war was finally over.

We were so relieved.

RADIO ANNOUNCER: It's official, it's all over!

It's total victory!

(cheering) ♪ ♪ NARRATOR: It's time to celebrate, not only the end of the war, but the remarkable new bomb that helped win it.

After years of secrecy, overnight "the Gadget" is big news.

And all of a sudden it's not only out, but here it is in the newspaper in front of me.

I bought a half a dozen papers of the different kinds, but, it-it-it was a shock.

♪ ♪ NARRATOR: It's a whole new era, the atomic age, with its own genesis story.

Secret cities, massive factories, the genius and the general are suddenly part of the culture.

And the press went wild.

RADIO ANNOUNCER: The atomic age loomed upon the threshold of history.

Suddenly the cat is out of the bag.

Well, what'd you think of that bomb we dropped on the Japs?

It was new.

An American invention.

RADIO ANNOUNCER: Thousands of able young scientists were called into service.

NORRIS: Los Alamos Laboratory.

RADIO ANNOUNCER: A secret laboratory in New Mexico.

It was work, work, work and more work.

Here it is, General Groves.

Plutonium.

Plutonium.

Uranium.

ANNOUNCER: Releasing unimaginable force.

The basic power of the universe.

RHODES: And at the center of all of this... NORRIS: Robert Oppenheimer... SHERWIN: father of the atomic bomb... ...one of the most famous people in all of America.

Trumps Einstein.

NARRATOR: The triumph of the bomb-- winning the war with science-- seems the perfect American success story.

Good thing it was dropped, ended the war, saved American lives, end of story.

♪ ♪ NARRATOR: The bomb seems to have brought an answer for how to end the war.

But it has also raised questions.

NORRIS: The question right away became when are the Soviets going to get a weapon, when are they going to get the bomb?

NARRATOR: Scientists who warned about Hitler having the bomb now worry about the U.S. and Soviets getting into a competition to build more and bigger bombs-- a nuclear arms race.

Little do they know it's already too late-- the race started the minute Stalin saw pictures of Hiroshima.

AMY KNIGHT: Suddenly this project that's on paper comes to reality.

And the destructive possibilities of this bomb were made clear.

SAVRANSKAYA: The Soviets felt very vulnerable.

And that spurs Stalin into action.

It's after the Hiroshima and Nagasaki bombing that Stalin creates the crash program to catch up and create a Soviet nuclear weapon.

NARRATOR: The Soviets have an invaluable head start, thanks to espionage.

Not one but two scientists at Los Alamos are spies.

RHODES: Klaus Fuchs, who was German, and another spy, who was an American, a graduate student at Harvard named Ted Hall.

NARRATOR: Having two independent sources inside Los Alamos is an incredible espionage coup.

NAFTALI: Well, imagine when Apple was designing the iPhone and if Apple's competitors had two people in the room with Steve Jobs, listening to Steve Jobs work through the various difficulties and snags.

They don't have to make the mistakes that Steve Jobs is making.

That's what made Fuchs and Hall so valuable and so extraordinary in the history of espionage and in the history of science.

NARRATOR: No one in the U.S. has any idea how close the Soviets are to getting the bomb.

NARRATOR: With the war over, Americans are getting back to normal, enjoying peace.

But the atomic bomb is a question mark hanging over the future.

ROBERT NORRIS: The Manhattan project is still in place.

What to do about the bomb, how many we have, how many to build.

NARRATOR: At the secret laboratory in New Mexico, the scientists are anxious to go home to their universities.

ALAN CARR: You had a group of young professors who had good jobs to go back to in academia, and you had young students who had not yet completed their studies.

GLEN McDUFF: You gotta remember, they're living here in little wooden shacks with coal stoves, eating bad food, on mud streets.

So as soon as the war ended, everybody left.

The town dropped from 3,000 to 4,000 people to, like, 1,000 people in just a matter of weeks.

NARRATOR: Robert Oppenheimer, whose vision created Los Alamos, is one who leaves.

The lab he built now seems destined to fade away.

In the summer of 1945, Trinity, Hiroshima, and Nagasaki opened the door to the new age.

But it won't be until a year later, in the summer of 1946, that major turning points will determine the future of the bomb.

We are here to make a choice between the quick and the dead.

NARRATOR: It begins in June at the United Nations, when the U.S. offers the world a plan to get rid of the bomb.

One: manufacture of atomic bombs shall stop.

Two: existing bombs shall be disposed of pursuant to the terms of the treaty.

NARRATOR: America will give up its atomic bombs if other countries pledge not to build them and agree to inspections.

It's an idea that will become known as "Trust but verify."

The Soviets refuse to pledge anything unless America gives up the bomb first.

NEWSREEL ANNOUNCER: The battle to save mankind from destroying itself is still deadlocked.

It is later than we think... NARRATOR: Debate will continue for months.

It's late June 1946, and the nuclear arms race will soon explode.

ANNOUNCER: Time now is measured in seconds.

MAN: Five, four, three, two, one... Fire!

(explosion) NARRATOR: Just a few weeks later, a huge fleet of warships is sent to the bottom of the Pacific Ocean by the atomic bomb.

Today, they still lie where they sank: Bikini Lagoon.

Here, in July 1946, the public would be invited to witness an atomic explosion for the first time.

The U.S. military would discover how vulnerable it was to its own bomb, and the future of Los Alamos Laboratory would be guaranteed.

All the result of an event appropriately named "Crossroads."

Crossroads is the brainchild of this man.

NORRIS: Lewis Strauss, or "Straws," as he liked to be called.

RICHARD RHODES: A curious figure of a man who had been a shoe salesman and had made himself very rich.

And then he was an admiral in the Navy, but he never sailed a ship.

Extremely politically ambitious.

NARRATOR: Strauss is worried about the navy.

How will the new atomic bomb affect its future?

Historically, what did we have in the country?

We had an army and a navy.

NORRIS: What does the bomb mean for each of them?

It's the thing to have.

It's a winning weapon.

Everybody wants it.

NARRATOR: But only the Air Force has it, and in 1946, the air force is still part of the army.

SHERWIN: People have been arguing that the navy's obsolete.

Now air forces will control how wars are fought and won.

JONATHAN WEISGALL: The traditional line in the navy during the Cold War, it was, "Remember, the Soviet Union is our adversary.

The army is our enemy."

NARRATOR: Lewis Strauss thinks he has the perfect answer to the navy's problem: a bomb test to prove navy ships can survive atomic weapons.

Operation Crossroads.

NORRIS: Sort of a contest between the navy and the air force in which air force bombers will try and sink navy ships.

NARRATOR: The first casualty in the contest is Leslie Groves.

The navy, not Groves, will be in charge of Crossroads.

They'll do the test in the middle of the Pacific Ocean, at the tiny island of Bikini.

The navy evicts the residents and assembles a target fleet.

Over 90 captured German, Japanese, and surplus U.S. warships will be bombed.

There will be three explosions: Able, Baker, and Charlie-- one in the air, two underwater.

Crossroads is a huge operation.

$100 million.

42,000 men.

240 ships, not counting the targets.

Instruments.

Cameras, cameras, and more cameras.

Film, miles and miles of it.

Animals, so doctors can study what the bomb does to living creatures.

And reporters from all over the world.

WEISGALL: It was a show.

It was a spectacle.

ANNOUNCER: At last, all was ready for Able day... NARRATOR: July 1, 1946, the show begins.

ANNOUNCER: Dave's Dream is roaring down the runway, engines singing.

NARRATOR: For the first test, Able, they'll drop the bomb from a plane.

ANNOUNCER: Bomb bay doors are open.

NARRATOR: The plane approaches.

The bomb is dropped.

(explosion) ANNOUNCER: Unfolded are a myriad of majestic, startling, and awesome effects, a panoply that only the cameras can record in faithful detail.

NARRATOR: The bomb, the same Fat Man model dropped on Nagasaki, has a force of 20,000 tons of TNT.

B-17 drones, flown by remote control, are sent into the mushroom cloud to take measurements.

(low rumbling) It's the first nuclear explosion to be witnessed by the public.

But the public is 18 miles away.

And after all the build-up...

I was a bit disappointed as to the size of the flash.

WEISGALL: You didn't see ships flying through the air, and the first reaction was, "Eh, the atomic bomb.

Not such a big deal."

NARRATOR: Three weeks later, a second test: Baker.

This time, the bomb will be underwater.

The scientists think it's a terrible idea.

They warn that exploding an atomic bomb underwater will create a "witch's brew" of radioactivity, releasing "enough plutonium to poison the entire armed forces of the U.S." McDUFF: They knew what was going to happen when you set off an underwater explosion.

It was going to make a lot of contamination.

But I guess they lost out to Admiral Blandy.

NARRATOR: Navy Admiral William Blandy is the man in charge of Crossroads.

And from the start, he's got a PR problem.

I am not an atomic playboy, as one of my critics labeled me, exploding these bombs to satisfy my personal whim.

Many considered it a boondoggle.

The bomb will not start a chain reaction in the water, converting it all to gas and letting all the ships on all the oceans drop down to the bottom.

There was a tremendous amount of pressure I think on the navy to try and convince the public that this was worthwhile.

ANNOUNCER: Bikini Atoll and Baker Day: the underwater explosion of the fifth atomic bomb.

The bomb and instruments are set into action.

Aboard the Los Alamos firing ship, nerves are stretched to the breaking point.

Five radio control circuits will set off the blast in this prelude to push-button warfare.

Three, two, one, fire!

(explosion) NARRATOR: An underwater shock wave is clearly visible.

In the first one second, two million tons of seawater are lifted into the air.

As the water rises, it creates a column nearly a half-mile wide.

Now, it starts to fall back.

The water falling out of the sky creates a base surge, like the mist at the bottom of a waterfall.

The surge, nearly a thousand feet tall, completely envelops the target ships.

No one has ever seen anything like it.

The sheer power and magnitude of the atomic bomb.

But so far, despite two of these bombs, the results look pretty good for the navy: 75 ships survive, less than 20 sunk.

WEISGALL: The navy felt that they came out of it with flying colors, and Blandy said, "Yes, the navy can withstand the atomic bomb."

NARRATOR: The navy plans to put sailors on these ships and sail them triumphantly back to the U.S.

But there's a problem.

ANNOUNCER: At first, there seemed to be little damage.

But succeeding days told a different story.

NARRATOR: The thousand-foot high wave of water that drenched the ships was highly radioactive.

The ships are now contaminated.

ANNOUNCER: Geiger counters rattle wildly.

The area is loaded with death-dealing gamma, neutron, and other lethal rays, and there is no complete protection against this terrifying invisible killer.

NARRATOR: At first, the navy simply doesn't believe it.

WEISGALL: You can't smell radiation, you can't feel it, and these navy guys were just gonna get back on their ships and survive the bomb.

NARRATOR: Now they have no idea what to do.

WEISGALL: The ignorance was rampant.

There was no real plan for decontamination.

NARRATOR: They try hosing down the ships with seawater.

Trouble is, the seawater itself is now highly radioactive.

And when sailors go back to their own ships to change clothes, they contaminate those ships too.

The man in charge of radiation safety, army doctor Stafford Warren, tries to cancel the operation.

WEISGALL: Stafford Warren doesn't want the sailors back on the ships, but it's pretty hard to go up against the entire U.S. Navy.

NARRATOR: In desperation, Stafford Warren gets a fish from the lagoon and places it against a piece of film.

The fish is so radioactive, it exposes the film all by itself.

ANNOUNCER: The glow was produced by the exposure of the film to radiation.

NARRATOR: Finally, Admiral Blandy and the navy are convinced.

Crossroads is halted.

It's been called the world's first nuclear disaster.

Only nine ships are ever successfully decontaminated.

Most of the rest are towed away and deliberately sunk.

The air force will remain the primary keeper of the bomb, for now.

But Crossroads turns out to be a good thing for Los Alamos.

CARR: I don't think the laboratory would have stayed in business very long had we not had a customer.

But the navy came in and gave us a job.

It gave us some work to do and kept the laboratory going through some very uncertain times.

NARRATOR: After July 1946, Los Alamos Lab will grow, building and testing more and more bombs over the coming decades.

(explosion) Crossroads also becomes part of popular culture.

Even today, the Baker shot remains the most enduring single image of the power of the bomb.

Just a few weeks after the second Crossroads shot, an unexpected event will give Americans another, much darker look at the bomb.

And for the first time, a major public debate about using it will begin.

On August 31, the latest issue of the New Yorker magazine appears.

On its cover, a whimsical portrait of Central Park on a summer day.

Inside, a very different portrait of another city on a summer day.

The entire issue is one single article: an essay by John Hersey about the experience of the people in Hiroshima told through the eyes of six survivors.

SHERWIN: One's a Catholic priest, one's a tailor's widow, a couple of them are doctors-- kinds of people that Americans can relate to.

NARRATOR: The special issue sells out in hours.

ANNOUNCER: "Hiroshima" by John Hersey.

This astounding report written for the New Yorker magazine has deeply affected thousands of Americans.

NARRATOR: Radio networks in England, Canada, Australia, and the U.S. preempt regular programming and do live readings by actors.

ANNOUNCER: This chronicle of suffering and destruction is not presented in defense of an enemy.

It is broadcast as a warning that what happened to the people of Hiroshima a year ago could next happen anywhere.

Chapter one, "A Noiseless Flash."

WOMAN: At exactly 15 minutes past 8:00 in the morning... TIM NAFTALI: No one had ever seen the consequences of a nuclear bomb.

And the knowledge of what this meant doesn't really soak in until afterwards.

NARRATOR: Now, in August '46, a year after Hiroshima, one essay is giving the world a whole new perspective on the bomb.

SHERWIN: It has enormous consequences.

It begins to make people rethink their attitudes towards nuclear weapons.

NARRATOR: But nuclear weapons are becoming the key to U.S. security.

LAURA McENANEY: Harry Truman and his advisors begin to think atomic weaponry can be the basis of diplomacy.

NARRATOR: Former Secretary of War Henry Stimson worries that Americans are turning against nuclear weapons, so he writes a response to the New Yorker piece to justify using the bomb.

SHERWIN: It says there were two choices: use the bomb or invade Japan.

And it is a false framework.

There were alternatives to both the bomb and an invasion.

NARRATOR: Would Japan have surrendered without our using the bomb?

There's no way of answering it one way or the other.

We cannot relive history.

If Truman had not used the bomb, why didn't he?

My son was killed because you didn't use the bomb?

An American airplane dropped... NARRATOR: The debate continues to this day.

All that is certain is that life in the atomic age is turning out to be more complicated than it seemed when the bomb first appeared.

ANNOUNCER: Yes, the atom is on its way to brighten our towns and to help manufacture our most dependable and indispensable household servant.

ANNOUNCER: The public flocked to atomic exhibits in search of understanding.

ELAINE TYLER MAY: The bomb had a certain kind of mystique, both terrifying and awe-inspiring.

And that was the whole other side of the atomic age: X-rays and medicine and atomic power, all these things that are gonna contribute to the good life.

ANNOUNCER: The atom has come to town.

♪ Atomic power, atomic power ♪ ♪ Was given by the mighty hand of God ♪ ♪ Atomic power, atomic power... ♪ Do you suppose that our appliances would run as well on atomic energy?

ANNOUNCER: Today's bonanza is a metal more precious than gold or silver.

There's uranium in them thar hills!

ANNOUNCER: It will protect your health, improve your food, bring you less costly living products and a greater measure of leisure and security.

♪ Hiroshima, Nagasaki ♪ ♪ Paid a big price for their sins ♪ ♪ When scorched from the face of earth ♪ ♪ Their battle could not win... ♪ MAN: The peaceful atom, no longer just a laboratory dream, is here today, working wonders.

♪ ♪ MAN: Did you know that someday, this machine of yours is going to be operating on atomic power?

They can run it on kerosene if they want to, just as long as I'm still at the switch.

ANNOUNCER: With the ever-increasing use of nuclear energy, more towns may eventually become atomic cities.

♪ It was given by the mighty hand of God... ♪ NARRATOR: One part of the early atomic age is still going strong today.

MAY: Where do we get the word "bikini"?

The designer of the bikini bathing suit designed it four days after the test on the Bikini Island because of its explosive, dangerous potential.

♪ It was given by the mighty hand of God.

♪ NARRATOR: While the country is adjusting to life in the atomic age, scientists in the original atomic city are looking to update the device that started it all.

Every bomb America has is still the original implosion design first tested at Trinity and dropped on Nagasaki: Fat Man.

Few realize how crude it actually is.

McDUFF: Fat Man was a science fair project.

I mean, this was not a production weapon.

It was hand-made, craftsmen fit all the pieces together, it takes about a week to build one.

NARRATOR: Two years after Crossroads, Los Alamos has a new design to try.

They'll explode three shots on the Pacific island of Eniwetok, a test code-named Sandstone.

McDUFF: Sandstone had three tests, X-ray, Yoke, and Zebra, and each one tested a new concept in weapons.

NARRATOR: This time, the public and press are not invited.

MAN: Six, five, four, three, two, one... (explosion) (explosion) (explosion) NARRATOR: Sandstone is the end of an era.

In January 1947, the bomb is put under civilian control, administered by the Atomic Energy Commission, AEC.

They replace the hand-made Fat Man with a new model, the first mass-produced nuclear weapon.

And they open a new lab to build the bombs Los Alamos designs.

It's the beginning of America's nuclear-weapons complex, a massive juggernaut that will drive bomb making and testing for decades, through multiple administrations to the end of the Cold War.

(explosion) The year after Sandstone, another test.

But this one isn't at Bikini, Eniwetok, or New Mexico.

It's in Kazakhstan.

RHODES: To the immense surprise of everyone, the Soviet Union tested its first atomic bomb.

And the balance of power was suddenly and dramatically shifted.

SERGEI KHRUSHCHEV: Testing the atomic bomb in Soviet Union was very important, because this is about balancing.

If you have this possibility, you're feeling yourself much safer.

SVETLANA SAVRANSKAYA: Psychologically, we are now on the same level with the United States.

Now, the United States cannot dictate to us.

(echoing): ♪ ...was given by the mighty hand of God... ♪ NARRATOR: If the power of the atom was God's gift to America, well, now he had given it to our enemy too.

NORRIS: It was a very, very scary moment for the United States: wow to respond now to the Soviet Union having a bomb?

SHERWIN: We need a quantum leap beyond the Soviets.

We have to stay way ahead of them.

NARRATOR: Some believe the answer is hydrogen fusion, the same energy that powers the sun.

A hydrogen, or thermonuclear bomb, could be far bigger than an atomic bomb.

There would be no theoretical limit to the size of the bomb you could make.

NARRATOR: The leading advocate for the hydrogen bomb is physicist Edward Teller.

McDUFF: Teller is kind of egotistical.

Rightly so-- he was really a smart guy-- but he was kind of hard to get along with.

SHERWIN: An idea man.

He'd have ten ideas a day.

One idea every month might be good, but he had ten ideas a day.

JOHN HOPKINS: He was always taken with the idea of going the next step beyond an atom bomb to a thermonuclear weapon, and I give him a tremendous amount of credit for sticking with this and campaigning for this.

NARRATOR: But no one knows how to build a hydrogen bomb.

It might even be impossible.

RHODES: We knew how to make atomic bombs.

We could fill warehouses with them.

But we didn't know how to make hydrogen bombs.

Why would you stop producing a sure thing to work on something you didn't know how to do?

NARRATOR: Moreover, some scientists believe this is a chance to save the world by choosing to stop.

CARR: This could be a turning point in human history.

We can pursue the hydrogen bomb, but we don't have to.

We can send a positive message to the international community, we can put pressure on the Soviets not to continue building nuclear weapons.

Basically, we can set a good example.

NARRATOR: Two months after the Soviet atomic bomb, a committee led by Robert Oppenheimer unanimously recommends against a crash program for a hydrogen bomb.

Lewis Strauss and Edward Teller are outraged.

But the decision is up to President Harry Truman.

NAFTALI: The debate over the hydrogen bomb involved the United States restraining itself without any ability to restrain the Soviets.

The Soviets had proven that they could build a bomb.

Well, that's a huge risk to take if you're president of the United States.

NARRATOR: The Soviets seem determined to expand.

They already control Eastern Europe.

In 1948, they cut off West Berlin, hoping to take that over as well.

To Harry Truman, the answer seems obvious.

MAY: Containment.

Contain the Soviet Union, don't allow it to expand, don't allow it to grow or to gain any more influence, and if we do, you know, it's just gonna creep and creep and creep until they'll be in our kitchens.

MAN: We need to speed up our work with other countries in strengthening our common defenses.

We are united in detesting Communist slavery.

NARRATOR: At the end of January 1950, Truman announces the U.S. will build a hydrogen bomb.

McENANEY: Truman decides to respond with an even bigger and more destructive weapon.

And this is the start of the arms race, this is the start of the escalation that will last for decades.

NARRATOR: Just days after Truman approves the H-bomb, physicist Klaus Fuchs, who worked at Los Alamos, is arrested for spying.

It suggested that this was sort of a leaky system and we had to plug the leaks.

CARR: It was a shock, and this was one of the first major events that set in motion the era of McCarthyism and the Red Scare.

NARRATOR: Five months later, Communist North Korea, backed by the Soviet Union, invades South Korea, which is backed by the U.S. ANNOUNCER: Spearheaded by tanks, in two days, they were attacking the capital city itself.

MAY: The Cold War wasn't even cold.

It was a hot war from pretty much the beginning.

There were proxy wars between the U.S. and the Soviet Union that were fought elsewhere.

NARRATOR: When the Korean War goes badly, the U.S. begins preparing to use atomic bombs and quickly discovers a problem.

(gunfire) RHODES: Korea is a very mountainous country, and there was concern that the bombs would not have much effect, that if we used the bombs, it might diminish their threat in the eyes of the Soviet Union.

So they were never used in Korea.

NARRATOR: As the Korean War drags on, the Soviets are doing atomic tests with bombers.

(explosion) Some atomic scientists have created a symbol to show how close the world stands to nuclear catastrophe: the Doomsday Clock.

At first, they set it at seven minutes to midnight.

Now, with a nuclear arms race accelerating, it's reset to three minutes to midnight.

Three minutes to global disaster.

With the threat of Soviet bombers carrying nukes, Americans have to adjust to a new reality: we could be hit at home.

McENANEY: In the Cold War, the front line was the front lawn.

MAY: You have to take care of yourself.

So how do you do that?

♪ Please duck and cover ♪ ♪ Duck and cover ♪ McENANEY: You could duck under a desk, you could take shelter in your basement and survive this.

MAN (on television): Our Congress leaves the responsibility for the personal initiative of each of us.

NARRATOR: The government does tests to see what would happen to typical Americans.

MAN: We begin with the question of shelter, for shelter might save our lives if we were far enough away from ground zero.

McENANEY: They put a family of mannequins dressed in J.C. Penney clothing inside a suburban ranch home.

And they furnished it, they put food in there, canned goods, and they blew them up.

MAN: Five.

Four.

Three.

Two.

One.

(loud explosion) In fact, the mannequins are blown into various states of dismemberment, but civil defense administrators, the lesson they took from this is that if you took the proper precautions, you could move through this.

NARRATOR: But only if you do the right things.

MAN: A house this neglected is the house that may be doomed in the atomic age.

A series of civil defense tests were made to discover the effects of atomic heat on American homes.

The house on the right, an eyesore-- old, unpainted wood.

And look at the paper, leaves and trash in the yard.

All the earmarks of untidy housekeeping.

The house in the middle in good condition with a clean, unlittered yard.

Let's see what happens under atomic heat.

♪ ♪ (loud explosion) ♪ ♪ The house on the right is the first to ignite.

The trash serves as kindling for the dry, weathered wood.

The lack of firesafe housekeeping has doomed this house to destruction.

The house in the middle cleaned up, painted up and fixed up, exposed to the same searing atomic heatwave did not catch fire.

LYNN EDEN: The point was if you clean up your yard and you don't have debris and things like that, you too can survive a nuclear blast.

MAN: It is your choice.

The reward may be survival.

♪ ♪ MAY: And it's your responsibility, not the government.

The government can't do it for you.

You have to take care of yourself.

And if you don't, if you're hurt, that is your fault.

NARRATOR: And just cleaning up may not be enough.

You may have to do some remodeling.

Well, folks, I'm glad you could come down to see my fallout shelter.

Just finished painting it last night.

This room can be put to other uses as well.

Yes, well, you could use this as an extra bedroom for company.

MAY: It really was the beginning of a kind of militarization where everyone is expected to be prepared.

Thick, heavy walls and ceiling protect against radiation.

The thicker the better.

It's this preparedness culture.

Well, this finishes my fallout shelter.

EDEN: So what is civil defense about?

Really, it's domestic theater for purposes of diplomacy.

McENANEY: Civil defense supported that idea that nuclear weapons should be the basis of American foreign policy, and in that sense, it was useful.

MAN: You'll learn how to save lives so well it won't be worth your while to drop any bombs on us.

EDEN: If our adversary thinks that the society can survive, it means that our threat to use nuclear weapons is more credible.

NARRATOR: Even as the government is trying to convince the public that nuclear war is survivable, in the Pacific, scientists are ready to test the first prototype of what Edward Teller calls "The Super"-- a hydrogen bomb.

The test is secret, but documented in a now- declassified government film.

If everything goes according to plan, we'll soon see the largest explosion ever set off on the face of the earth.

NARRATOR: The device is more science project than weapon, not so much a bomb as a building.

The liquid hydrogen fuel must be chilled to 400 degrees below zero, so part of the bomb is a refrigeration plant.

The whole thing weighs over 70 tons.

All to see if the thermonuclear concept will work.

This is the first full-scale test of a hydrogen device.

If the reaction goes, we're in the thermonuclear era.

MAN (over PA): It is now 30 seconds to zero time.

Put on goggles or turn away.

Do not remove goggles or face first until ten seconds after the first light.

Three, two, one... (explosion) NARRATOR: It explodes with a force of ten million tons of TNT, 600 times more powerful than the bomb that destroyed Hiroshima.

MAN: (speaking Russian) NARRATOR: Just nine months later, the Soviets explode their first hydrogen bomb.

It's less powerful than America's H-bomb, but it's small enough to be carried by a plane.

The Soviet Union has solidified control in eastern Europe, acquired the atomic bomb, supported a war in Korea, and now has a deliverable hydrogen bomb.

The U.S. is in the midst of a Red Scare, a quest to root out anyone who can be blamed for Communist success.

In this climate of fear and recrimination, Robert Oppenheimer is about to become a target, the victim of Lewis Strauss.

NORRIS: He is a horrible, horrible person.

Really one of the evil men in this story.

NORRIS: He's already looking for a way to attack Oppenheimer and humiliate him.

NARRATOR: Strauss has never forgiven Oppenheimer for opposing a crash program to develop a hydrogen bomb.

When President Eisenhower makes Strauss chairman of the Atomic Energy Commission, he sees his chance for revenge.

RHODES: The first thing he did when he took office was to begin a process that would lead to having Oppenheimer's security clearance lifted.

NARRATOR: The AEC has a hearing.

Strauss picks the judges and the prosecutor.

He gives them secret files on Oppenheimer dating back to the '30s, and he enlists the FBI.

SHERWIN: The FBI is tapping Oppenheimer's phone and his attorney's phone, and feeding this information to the prosecutor.

It is totally a kangaroo court.

RHODES: They went back over his life step by step, mistake by mistake.

People come to his defense, people attack him.

RHODES: The women in his life.

NORRIS: All of his Communist past.

And Oppenheimer got smaller and smaller and smaller, sitting in this hard chair in the middle of the security hearing.

NARRATOR: The moment of truth comes when Edward Teller is asked, "Do you believe Oppenheimer is a security risk?"

RHODES: And Teller very cleverly never said, "Yes, I do."

What he said was, "I would feel more secure if Oppenheimer were no longer asked to advise the government."

And with that, he drove in the final nail.

NARRATOR: The father of the atomic bomb is stripped of his clearance, kicked out of government forever.

LILLI HORNIG: You know, it was witch hunt time.

I thought that was disgusting, frankly.

SHERWIN: It achieved exactly what his enemies wanted to achieve.

It destroyed him.

It killed him spiritually.

NARRATOR: But Teller pays a price.

The hatred to Edward was so thick you could cut it with a knife.

The people who dealt most closely with Edward, I think at Los Alamos at least, disliked him for the rest of his life.

NARRATOR: Even as the AEC is going after Oppenheimer, in the Pacific, another test: America's first practical H-bomb.

If it works, a deliverable thermonuclear weapon.

(explosion) On March 1, 1954, it becomes apparent that the bomb does indeed work, only too well.

Because of design errors, it's twice as powerful as predicted: 15 megatons, equal to 15 million tons of TNT.

Approximately 1,000 times as powerful as Little Boy.

This is a massive, massive weapon.

NARRATOR: The mushroom cloud rises over 15 miles, spreading radioactivity through the atmosphere.

Fallout contaminates inhabited islands and a Japanese fishing boat, ironically named Lucky Dragon.

One of the Japanese fishermen dies.

Over 200 islanders get sick.

The test was secret, but the fallout makes it an international incident.

NORRIS: It brought worldwide attention to the fact of atmospheric testing.

You know, should we be testing in the atmosphere, when all that happens is this radiation is gonna get in the wind currents and expose everybody to radiation?

NARRATOR: The incredible power of the H-bomb reveals the futility of civil defense.

McENANEY: The concern before the hydrogen bomb was, could we take shelter?

What the hydrogen bomb tests reveal is that that is inadequate.

There may be no safety, except run.

ANNOUNCER: It was estimated over four million would have died in New York City.

NARRATOR: If surviving a Soviet H-bomb is impossible, the only option is to deter them from attacking in the first place.

To do that, President Eisenhower creates a new policy.

Any Soviet aggression will be met with massive nuclear retaliation delivered by the Strategic Air Command: SAC.

ANNOUNCER: The air force maintains part of its bomber fleet airborne at all times, prepared to proceed to specific targets.

NARRATOR: SAC is led by Curtis LeMay.

LeMay realizes that the bomb has forever changed war.

RHODES: He saw very early that wars would last for days or even hours, and everything had to happen right up front.

NARRATOR: LeMay plans a massive first strike on the Soviet Union, what he calls a "Sunday Punch."

Ready to go at a moment's notice, his crews drill constantly.

(sirens blaring) ANNOUNCER: V47s and V52s taking off from bases throughout the free world.

WALTER BOYNE: All of a sudden, you've got 90 airplanes that are departing this airport, nuclear weapons on board.

You take off, you don't know whether it's really a mission or not.

Everything is so classified, you won't get those coded instructions until you are airborne.

And you know that at eight or ten other bases, the same damn thing is happening: that this flow of airplanes are in the air, they will be coming towards the Soviet Union, and unless the Soviet Union backs down shortly, it's not gonna be around.

ANNOUNCER: When this red phone is picked up, direct lines to SAC bases on four continents are seized.

NARRATOR: Massive retaliation means U.S. defense is increasingly dominated by the air force.

RHODES: The air force controlled 47% of the national defense budget, at which point the navy and the army began thinking, "Wow, we better get some atomic bombs too."

NARRATOR: As the military services compete, America's nuclear stockpile grows and diversifies.

McDUFF: Los Alamos was happy to make it, and the military was happy to pay for it.

And so every time they asked for something, the lab responded, "Sure, no problem."

JOHN HOPKINS: Nuclear weapons were viewed as just regular weapons, only bigger.

NORRIS: How many different kinds can we fabricate?

CHUCK LOEBER: Big bombs, little bombs, big warheads, little warheads.

NARRATOR: A nuclear cannon for ground troops.

Even a one-man backpack nuke, a way to stop thousands of Soviet tanks from invading Germany.

ANNOUNCER: One nuclear round will be detonated here 26 minutes prior to the attack.

JOHN ANDERSEN: Blocking avenues of approach by barriers of flooding and cratering and land sliding, attacking autobahns or highways or railroads or bridges.

(explosion) Atomic demolition munitions.

NARRATOR: Eventually, the drive to make a nuclear version of anything and everything gets a little out of hand.

HOPKINS: There was a nuclear bazooka, which I think probably is a contender for being the most ridiculous.

ANNOUNCER: It detonated perfectly, releasing its lethal radiation.

LOEBER: Some of the physicists said we could actually develop a nuclear hand grenade.

The only problem was finding somebody dumb enough to throw it.

NORRIS: So the American stockpile blossoms.

LOEBER: By 1947, we had a stockpile of 13.

By 1953, we had over 1,100.

By the late '60s, we had over 31,000 nuclear weapons and 36 different types.

McDUFF: I kind of wonder, exactly, did you really need all this?

But I think a lot of it was the military thought they did.

And a lot, I think, is just political.

You know, "We have more than you!

You know... NARRATOR: The ultimate example of "we have more than you" comes in October 1961, when the Soviets detonate the largest bomb in human history: Tsar Bomba.

50 megatons-- 50 million tons of TNT.

McDUFF: When the pilot landed, he said the plane was highly warped, skin buckled, and the pilot never flew again.

He said he had done his job for the motherland, and he retired after the drop.

NARRATOR: But it's good for nothing except symbolism.

McDUFF: A bomb this big is not really of any utility.

You don't kill a lot more people with a gigantic bomb like that than you can with a couple little bombs.

BOYNE: You had two superpowers, and you had to suppress the other superpower from making a first strike.

And the only way you could do that was to be so strong that if they did strike you first, they would be wiped out.

LOEBER: Mutual assured destruction: MAD.

And looking back, I think it was.

On the other hand, by both sides being so strong that they knew they could destroy each other... ...it kept the peace.

NARRATOR: Until it almost didn't.

In October 1962, Soviet leader Nikita Khrushchev sees a chance to make a bold stroke in America's backyard.

NAFTALI: Khrushchev decides to put missiles in Cuba in order to change the balance of power.

NARRATOR: Even today, new details about Khrushchev's power play are still coming to light.

SAVRANSKAYA: We still don't know the full story.

But it was not just the missiles.

The Soviets were planning to create a massive military base in Cuba, the most powerful Soviet military base in the world.

He was thinking of a remapping of the Cold War relationship.

Dramatic.

Unprecedented.

But to make it work, Khrushchev had to do it secretly because if the United States knew that missiles were going to Cuba, we would stop them.

NARRATOR: It almost works.

But before the Soviets can complete the installation, a U.S. spy plane discovers the plan.

The showdown begins with a speech.

It was about 9:00 in the evening that they announced this speech of the president to the nation.

Good evening, my fellow citizens.

This government has maintained the closest surveillance of the Soviet military build-up on the island of Cuba.

And my father told me, "I think they discovered missiles."

A series of offensive missile sites is now in preparation on that imprisoned island.

SAVRANSKAYA: The Soviets were very worried.

They were kind of expecting Kennedy to announce not just the blockade, but maybe an invasion of Cuba.

And then it will be strong possibility of the real nuclear war, and it will be end of the world.

It shall be the policy of this nation to regard any nuclear missile launched from Cuba against any nation in the Western hemisphere as an attack by the Soviet Union on the United States requiring a full retaliatory response upon the Soviet Union.

"Full retaliatory response on the Soviet Union."

And I knew exactly what a full retaliatory response meant and what the consequences of that would be.

MAY: We would consider bombing you with atomic weapons.

To see the president of the United States go on national television, tell the world that could happen, that got people's attention.

ANNOUNCER: At United Nations headquarters in New York, the Cuban crisis is the one and only subject of discussion.

The issue which confronts the security council is grave.

NARRATOR: As Kennedy considers invading Cuba, he calls former president and general Dwight Eisenhower for advice.

NARRATOR: Kennedy has no idea that tactical nuclear weapons are already in Cuba.

SAVRANSKAYA: They were thinking, "Well, if the Americans land in Cuba, "then we would have to use "at least tactical nuclear weapons to repel them, and maybe even mid-range weapons."

Missile officers in Cuba had authorization from the Soviet Union to launch those missiles rather than to allow them to be destroyed.

NAFTALI: Now, imagine if Marines had landed on the beaches of Cuba and had been met by a volley of tactical nuclear weapons.

(alarm blaring) PERRY: Very scary days.

I truly thought we were going to war.

Really, every time I went into that office during the day, I thought it was going to be my last day on earth.

(alarm blaring) NARRATOR: In the end, Kennedy and Khrushchev both stare into the nuclear abyss and step back.

KHRUSHCHEV: Two leaders took control of this crisis.

They decided, "No, we will not start the war.

We will try to resolve this diplomatically."

There is a great story of nuclear learning here, when they realized what the consequences could be.

Khrushchev really changed his position in a radical way very quickly.

NARRATOR: Khrushchev withdraws the missiles.

In return, Kennedy secretly agrees to remove U.S. missiles along the Soviet border.

Cuban Missile Crisis was a much closer call than I think people to this day really realize.

Both sides were behaving really recklessly, really recklessly.

But once they saw what the real danger looked like, then both of them made concessions and became very reasonable.

And you can even say that the Cuban Missile Crisis began the process of arms control.

As president of the United States, I now sign the instruments of ratification of this treaty.

NARRATOR: Nine months after the Missile Crisis, the U.S., Soviets, and Britain agree on the first Test Ban Treaty, which bans nuclear tests in the atmosphere, in space, and underwater.

And within a year, the first direct hotline is established between Washington and Moscow.

Even before the Missile Crisis, opposition to the bomb had been building, often spearheaded by women.

MAY: "Don't give irradiated milk to my children!"

You know, you have a bomb test, the winds blow radiation to the fields where the cows eat the grass, and then you get the milk and we serve it to our children?

No, we're not going to do this anymore.

RHODES: So many mothers marched against atmospheric nuclear testing that the United States government finally said, "All right, we'll put the tests underground."

RECORDED VOICE: Five, four, three, two, one, zero.

(explosion) NARRATOR: Underground tests also explore the potential to use the bomb for landscaping on a gigantic scale, possibly excavating road cuts, harbors, canals.

The testing that began in 1945 and continued through 1962 included over 200 nuclear explosions.

Once it moved underground, there were 800 more before all U.S. testing stopped in 1992.

But moving testing underground was only the first step.

Books and films began to explore what nuclear war and its aftermath would mean.

Grim dramas like On the Beach... Fail Safe...

The dark satire of Dr. Strangelove... No Nukes, a ground-breaking concert, film, and rally...

The Day After, a television movie that draws 100 million viewers and becomes a major cultural event... And War Games, which cautions that in nuclear war, the only winning move is not to play.

Slowly but surely, the public is leading the leaders.

What began in 1963 with the first Test Ban Treaty leads to other agreements-- attempts to slow down the build-up of nuclear weapons.

By 1986, Ronald Reagan is president, George Shultz his secretary of state.

In October, Reagan meets Soviet leader Mikhail Gorbachev in Reykjavik, Iceland, and something remarkable happens.

GEORGE SHULTZ: President Reagan's on one end of the table and I'm sitting next to him.

Gorbachev's on the other end of the table.

Shevardnadze's sitting next to him.

And we talked about eliminating nuclear weapons.

NAFTALI: He and Gorbachev, in a totally unscripted, totally improvisational way, moved closer to a superpower agreement to denuclearize the world than ever happened before or has happened since.

Such a dramatic moment, where two presidents of these superpower enemies suddenly find this common platform, common wish.

NARRATOR: But the common wish to get rid of the bomb ultimately proves impossible.

The sticking point is a new U.S. technology called Star Wars, promoted by Edward Teller.

NAFTALI: It was a technology the Soviets did not have, and it was a technology that they felt could be used to make it impossible for the Soviets to have a nuclear deterrent.

SAVRANSKAYA: And Gorbachev was not able to accept that.

(cheering) NARRATOR: The Cold War is thawing.

Three years after Reykjavik, the Berlin Wall comes down.

In 1991, Mikhail Gorbachev dissolves the Soviet Union.

All without the bomb being used.

We got out of it with the skin of our teeth, we had a couple of close calls along the way, and I think, you know, we were lucky.

These two countries were able to end the most dangerous, the most protracted confrontation in history.

NARRATOR: At the height of the nuclear arms race, the U.S. and Soviet Union together had over 60,000 nuclear weapons.

SHERWIN: It's absolutely insane, and when we get enough distance from this, people will look back on it as a moment of humanity's most extraordinary insanity.

BOYNE: It was an overkill by 5,000% on both sides.

It was stupid, it was wasteful, it would have been the ultimate catastrophe, and yet it worked.

NAFTALI: The bomb is what keeps this whole cycle a cold war, not a hot war.

Without the bomb, at some point we would have been fighting each other.

AMY KNIGHT: The legacy of the bomb was that it really changed the nature of global politics.

It was just a whole new ballgame.

KHRUSHCHEV: The bomb bring the understanding to the politicians that now, you cannot win the war.

Because if you will start the war, you will lose more than you will gain.

NARRATOR: Today, besides the U.S. and Russia, six other nations also have the bomb, plus South Africa, which had it and got rid of it, and Israel, which will not confirm or deny having it.

NORRIS: We don't have control over them or what they might do with it.

The scariest one is India and Pakistan.

NARRATOR: Some experts believe even a limited nuclear war between India and Pakistan would be catastrophic for all of us.

RHODES: There would be so much smoke and smog from the cities burning that there would be a sort of a nuclear winter around the whole world, dropping average temperatures just enough to cause crop failures worldwide, and about two billion human beings would starve to death.

PERRY: People do not understand the danger.

They don't understand the likelihood it's going to happen is really high, and they don't understand the magnitude.

NARRATOR: Over 70 years ago, a few scribbles on a blackboard opened the door to a new reality.

Fateful decisions set the world on a path to nuclear weapons.

HORNIG: I don't feel any guilt or blame about it.

I think my view really is if we hadn't done it, somebody else would have, and it would be with us in any case.

(explosion) NARRATOR: There is no going back.

The knowledge of how to destroy ourselves is here to stay.

It appears that our task is learning how to live with it.

RHODES: I think what should give us hope is that in all the decades since 1945, not one nuclear weapon has been exploded in anger anywhere in the world.

We've managed, somehow, to keep our thumb off the button.

And let's hope we continue.

"The Bomb" is available on DVD.

To order, visit shopPBS.org, or call 1-800-play-PBS.

Captioned by Media Access Group at WGBH, access.wgbh.org