Nuclear weapons haven’t been tested in the United States since 1992. Find out why, and what could happen if the hiatus ends.

The world passed a nuclear milestone this week. And, perhaps surprisingly given the recent run of saber-rattling from the likes of Russia and the United States, it’s a positive one.

Minutes before walking into a high-stakes meeting with Chinese President Xi Jinping this past week, President Donald Trump announced what could prove to be a stunning shift in American nuclear policy.

In 1961, the Soviet Union detonated the largest nuclear weapon ever built, a test so powerful it sent shockwaves around the ...

Resuming full testing of nuclear weapons — as President Donald Trump called for last week — would be unnecessary, costly, undermine nonproliferation efforts, and empower the nation’s adversaries to ...