The Manhattan Project

North Korea’s dictator, Kim Jong Un, vows to annihilate the U.S. with a “hail of fire.” President Trump threatens to “totally destroy North Korea.” The tensions have brought the world closer to a nuclear conflict than at any time since the end of the Cold War (1947-91).

 Although North Korea’s ability to attack the U.S. mainland with nuclear missiles is still an open question, any war waged with atomic weapons could have horrific consequences, leveling whole cities and killing millions of people.

Where did such monstrous firepower come from? It all began 75 years ago, in September 1942, when the U.S. Army took command of a top-secret effort called the Manhattan Project. The project’s goal was to produce a powerful new weapon that could be used against America’s enemies in World War II (1939-45). The result would be the world’s first atomic bomb. In 1945, U.S. warplanes dropped two atom bombs, on the Japanese cities of Hiroshima and Nagasaki, bringing Japan to its knees and quickly ending the war—and changing the nature of warfare forever.  

Today, as nuclear fears again make headlines, we’re still grappling with the destructive power that the Manhattan Project unleashed.

North Korea’s dictator, Kim Jong Un, vows to wipe out the U.S. with a “hail of fire.” President Trump threatens to “totally destroy North Korea.” The tensions have brought the world closer to a nuclear conflict than at any time since the end of the Cold War (1945-91).

North Korea’s ability to attack the U.S. mainland with nuclear missiles is still an open question. But any war waged with atomic weapons could have horrific consequences. These type of weapons could level whole cities and kill millions of people.

Where did such monstrous firepower come from? It all began 75 years ago. In September 1942, the U.S. Army took command of a top-secret effort called the Manhattan Project. The project’s goal was to create a powerful new weapon to be used against America’s enemies in World War II (1939-45). The result would be the world’s first atomic bomb. In 1945, U.S. warplanes dropped two atom bombs, on the Japanese cities of Hiroshima and Nagasaki. The bombings brought Japan to its knees and quickly ended the war. This moment changed the nature of warfare forever.

Today, nuclear fears are making headlines again. And we’re still grappling with the destructive power that the Manhattan project unleashed.

World War II began in Europe when German dictator Adolf Hitler attacked neighboring Poland in September 1939, with a goal of conquering all of Europe. Only a month before, German-born physicist Albert Einstein—a Jew who fled the Nazis for the U.S.—had written to President Franklin D. Roosevelt, warning that German scientists might be using new advances in physics to try to engineer a nuclear weapon. Einstein explained that building such a weapon would involve splitting the nucleus of an atom, a process called fission. Using the element uranium, this process could cause a chain reaction that would unleash an amount of energy millions of times more destructive than dynamite.

Roosevelt ordered a study. Then in December 1941, Japan attacked the U.S. Naval base at Pearl Harbor, Hawaii. The U.S. joined World War II against Japan and its ally Germany, and Americans were soon fighting and dying in Europe and Asia. The quest for an atomic bomb took on a new urgency.

About 500,000 people, including thousands of scientists, were tapped for the effort, named for the location of its first office, in New York City. Secret labs and test sites were scattered in places including Tennessee, Washington State, and New Mexico.  

“The Manhattan Project was so massive that its tendrils stretched throughout the military and scientific communities,” says Karen Harpp, a nuclear weapons expert at Colgate University in Hamilton, New York.

The technical challenges of making such a bomb were immense. “Because they were doing this for the first time, it wasn’t even clear that it could be made to work correctly,” says Alex Wellerstein, a nuclear historian at Stevens Institute of Technology in Hoboken, New Jersey. And then, he says, “It had to be made small enough to fit inside of an airplane.”

Finally, in July 1945, at a remote spot in New Mexico called Alamogordo, the first atomic bomb was detonated. The explosion, which had the force of 20,000 tons of dynamite, generated a giant mushroom cloud crowned by a ball of fire that reached 30,000 feet into the air.

“We knew the world would never be the same,” lead scientist J. Robert Oppenheimer later said.

Officials were relieved. The bomb worked. Now, what would they do with it? That grave decision fell to the new president, Harry S. Truman. (Roosevelt had died in office in April, never having told his vice president about the Manhattan Project. Truman learned of it only after becoming president.)

The Germans had already surrendered in May, ending the war in Europe. But the Japanese kept fighting. Truman had to decide whether to risk an invasion of Japan that could claim hundreds of thousands of American lives—or drop the bomb.

World War II began in Europe when German dictator Adolf Hitler attacked neighboring Poland in September 1939. He intended to conquer all of Europe. Only a month earlier, German-born physicist Albert Einstein—a Jew who fled from the Nazis to the U.S.—had written to President Franklin D. Roosevelt. Einstein warned that German scientists might be using new advances in physics to try to engineer a nuclear weapon. He explained that building such a weapon would involve splitting the nucleus of an atom, a process called fission. Using the element uranium, this process could cause a chain reaction that would unleash an amount of energy millions of times more destructive than dynamite.

Roosevelt ordered a study. Then in December 1941, Japan attacked the U.S. Naval base at Pearl Harbor, Hawaii. The U.S. joined World War II against Japan and its ally Germany. Americans were soon fighting and dying in Europe and Asia. The quest for an atomic bomb took on a new urgency.

About 500,000 people, including thousands of scientists, were tapped for the effort. The project was named after the location of its first office, in New York City. Secret labs and test sites were scattered in Tennessee, Washington State, and New Mexico.

“The Manhattan Project was so massive that its tendrils stretched throughout the military and scientific communities,” says Karen Harpp, a nuclear weapons expert at Colgate University in Hamilton, New York. 

The technical challenges of making such a bomb were immense. “Because they were doing this for the first time, it wasn’t even clear that it could be made to work correctly,” says Alex Wellerstein, a nuclear historian at Stevens Institute of Technology in Hoboken, New Jersey. “It had to be made small enough to fit inside of an airplane.”

Finally, in July 1945, at a remote spot in New Mexico called Alamogordo, the first atomic bomb was detonated. The explosion had the force of 20,000 tons of dynamite. It generated a giant mushroom cloud crowned by a ball of fire that reached 30,000 feet into the air.

“We knew the world would never be the same,” lead scientist J. Robert Oppenheimer later said. 

Officials were relieved. The bomb worked. Now, what would they do with it? That grave decision fell to the new president, Harry S. Truman. Roosevelt had died in office in April. He never told his vice president about the Manhattan Project. Truman learned of it only after becoming president.

The Germans had already surrendered in May, ending the war in Europe. But the Japanese kept fighting. Truman had two options. He could either risk an invasion of Japan that could claim hundreds of thousands of American lives or he could drop the bomb.

Truman would later say it was an easy decision to use the new weapon. On August 6, a U.S. warplane dropped a bomb nicknamed “Little Boy” on Hiroshima. The explosion destroyed more than five square miles of the city. Some 80,000 people were killed instantly. Tens of thousands more would die from radiation sickness later on.

Three days later, the U.S. dropped a second bomb, nicknamed “Fat Man,” on Nagasaki, the blast alone killing as many as 80,000 more Japanese. On August 15, Emperor Hirohito announced his country’s surrender. World War II was over.

Truman would later say it was an easy decision to use the new weapon. On August 6, a U.S. warplane dropped a bomb nicknamed “Little Boy” on Hiroshima. The explosion destroyed more than five square miles of the city. Some 80,000 people were killed instantly. Tens of thousands more would die from radiation sickness later on.

Three days later, the U.S. dropped a second bomb, nicknamed “Fat Man,” on Nagasaki. The blast alone killed as many as 80,000 more Japanese. On August 14, Emperor Hirohito announced his country’s surrender. World War II was over.

Since 1945, many Americans have questioned whether the atomic bomb was worth the devastation it caused. It probably saved many thousands of American lives, forcing a quick end to the war. But it heralded a new world in which nations would have the power to annihilate one another as never before.

By 1949, the Soviet Union had its own bomb, leading to an “arms race” with the U.S. As more advanced missiles were developed, officials in both nations adopted a policy of “mutually assured destruction” (MAD). That meant neither side dared to strike the other for fear of being wiped out in return.

That principle was put to the test in 1962, when the Soviets placed nuclear missiles in Cuba, just 90 miles from Florida. President John F. Kennedy demanded that the missiles be removed and after 13 tense days, the Soviets backed down. It was the closest the world had ever come to all-out nuclear war.

Since 1945, many Americans have questioned whether the atomic bomb was worth the devastation it caused. It probably saved many thousands of American lives, forcing a quick end to the war. But it heralded a new world in which nations would have the power to annihilate one another as never before.

By 1949, the Soviet Union had its own bomb. This led to an “arms race” with the U.S. As more advanced missiles were developed, officials in both nations adopted a policy of “mutually assured destruction” (MAD). That meant neither side dared to strike the other for fear of being wiped out in return.

That principle was put to the test in 1962, when the Soviets placed nuclear missiles in Cuba, just 90 miles from Florida. President John F. Kennedy demanded that the missiles be removed. After 13 tense days, the Soviets backed down. It was the closest the world had ever come to all-out nuclear war.

Since then, the United Nations (U.N.) and individual nations have worked to limit nuclear arms. The Nuclear Nonproliferation Treaty (1970), signed by 191 countries, promised to eventually rid the world of those weapons.

But that hasn’t happened. Nine countries today possess nearly 15,000 nuclear warheads (see “The Nuclear Club,” below). Russia (which inherited the Soviet Union’s stockpile) and the U.S. together have more than 90 percent of them.

Experts warn that a regional conflict between smaller nuclear powers, like longtime enemies Pakistan and India, could draw other nations into a wider war. They also worry that a nuclear weapon could be stolen from an unstable government and fall into the hands of terrorists.

The U.S. and Israel are especially concerned about Iran, a foe of both nations that once seemed like it was on the path to obtaining nuclear weapons. In 2015, Iran reached a deal with the U.S. and five other countries to temporarily limit its nuclear program to only peaceful purposes in return for the lifting of economic sanctions that were crippling the country.

But President Trump doesn’t trust Iran. He’s blasted the agreement, made under former President Barack Obama, as “an embarrassment” to the U.S. and threatened to withdraw from it. Some critics believe that could cause Iran to restart its nuclear weapons program.

Since then, the United Nations (U.N.) and individual nations have worked to limit nuclear arms. The Nuclear Nonproliferation Treaty (1970) promised to eventually rid the world of those weapons. It was signed by 191 countries.

But that hasn’t happened. Nine countries today possess nearly 15,000 nuclear warheads (see “The Nuclear Club,” below). Russia, which inherited the Soviet Union’s stockpile, and the U.S. together have more than 90 percent of them.

Experts warn that a regional conflict between smaller nuclear powers, like longtime enemies Pakistan and India, could draw other nations into a wider war. They also worry that a nuclear weapon could be stolen from an unstable government and fall into the hands of terrorists.

The U.S. and Israel are especially concerned about Iran, a foe of both nations that once seemed like it was on the path to obtaining nuclear weapons. In 2015, Iran reached a deal with the U.S. and five other countries to temporarily limit its nuclear program to only peaceful purposes in return for the lifting of economic sanctions that were crippling the country.

But President Trump doesn’t trust Iran. He’s blasted the agreement, made under former President Barack Obama, as “an embarrassment” to the U.S. and threatened to withdraw from it. Some critics believe that could cause Iran to restart its nuclear weapons program.

North Korea became a nuclear power a decade ago, despite efforts by the U.S. and the U.N. to prevent the rogue state from acquiring nuclear weapons. Kim Jong Un has recently tested intercontinental ballistic missiles capable of reaching some U.S. cities, but it’s unclear whether North Korea has the capability to successfully mount a warhead on them.

Still, North Korea is next door to U.S. ally South Korea, and the threat of a nuclear attack on a major South Korean city is very real.

North Korea became a nuclear power a decade ago, despite efforts by the U.S. and the U.N. to prevent the rogue state from acquiring nuclear weapons. Kim Jong Un has recently tested intercontinental ballistic missiles capable of reaching some U.S. cities. But it’s unclear whether North Korea has the capability to successfully mount a nuclear warhead on them.

Still, North Korea is next door to U.S. ally South Korea. The threat of a nuclear attack on a major South Korean city is very real.

Could nuclear arms ever be eliminated? Peace activists have long pursued such a goal. But skeptics say that no nation will give up its nukes if it knows that another has them.

“We have to be realistic,” says Nikki Haley, the U.S. Ambassador to the U.N. “Is there anyone who thinks that North Korea would ban nuclear weapons?”

That hasn’t stopped the International Campaign to Abolish Nuclear Weapons (ICAN), the group that won the Nobel Peace Prize last month. ICAN knows it won’t be easy to achieve its goal of ridding the world of nuclear arms. But it believes that through negotiations, world leaders can gradually be convinced to destroy all of those weapons.

Wellerstein, the historian, also thinks that having the U.S. and North Korea talk—rather than simply threaten each other—is the only way forward.

“We hope that, away from the cameras, the leaders of these countries understand the dangers,” he says. “Hopefully, this will lead people to search for ways to make the world safer.”

Could nuclear arms ever be eliminated? Peace activists have long pursued such a goal. But skeptics say that no nation will give up its nukes if it knows that another has them.

“We have to be realistic,” says Nikki Haley, the U.S. Ambassador to the U.N. “Is there anyone who thinks that North Korea would ban nuclear weapons?”

That hasn’t stopped the International Campaign to Abolish Nuclear Weapons (ICAN). The group won the Nobel Peace Prize last month. ICAN knows it won’t be easy to achieve its goal of ridding the world of nuclear arms. But it believes that through negotiations, world leaders can gradually be convinced to destroy all of those weapons.

Wellerstein, the historian, also thinks that having the U.S. and North Korea talk—rather than simply threaten each other—is the only way forward.

“We hope that, away from the cameras, the leaders of these countries understand the dangers,” he says. “Hopefully, this will lead people to search for ways to make the world safer.”