The National Nuclear Security Administration is a semi-autonomous agency within the Department of Energy that oversees the U.S. stockpile of thousands of nuclear weapons. Officials were given hours to fire hundreds of employees.

A thousand feet beneath the desert, the United States conducts experiments to verify that its weapons work. But some fear a live test could come soon.

The Stockholm International Peace Research Institute report says it hasn't seen nuclear weapons playing such a prominent role in international relations since the Cold War.

Russian President Vladimir Putin issued explicit nuclear threats to the West, even as he assured Russians their country could both win the war in Ukraine and thrive economically.

The world's major nuclear powers haven't tested a bomb this century, but experts worry that may be about to change.

As President Biden and Group of Seven leaders gathered in Hiroshima, people in Japan wanted the setting to act as a powerful symbol for consensus toward banning nuclear arms.

Catch up on key developments and the latest in-depth coverage of Russia's invasion of Ukraine.

Putin said the plan was in response to Britain's decision this past week to provide Ukraine with armor-piercing rounds containing depleted uranium.

The launch comes a day after the U.S. and South Korea held tabletop exercises simulating a North Korean nuclear attack.

A giant laser facility in Livermore, Calif., says it has created net energy from nuclear fusion. It's an important breakthrough, but fusion power remains a distant dream.

Experts in Russian doctrine worry that as the war in Ukraine gets more desperate, Russia might be tempted to detonate a nuclear weapon.

North Korean leader Kim Jong Un said his country will never abandon the nuclear weapons it needs to counter the United States, which he accused of pushing to weaken the North's defenses.

Russian President Vladimir Putin gave orders to his nation's nuclear forces over the weekend, but their exact meaning is unclear. Russia has more nuclear weapons than any other nation.

As North Korea's dictator marks a milestone on Friday, he might be facing his toughest moment yet, as crushing sanctions, the pandemic and growing economic trouble converge

Citing President Biden's speech to Congress, North Korea says the United States will face a grave situation if it continues to pursue its "hostile policy" toward the country's nuclear program.