New weapons, unstable nations, and terrorism are raising the nuclear stakes. Is a doomsday attack more likely? Here’s everything you need to know about the new nuclear arms race:

How many nuclear weapons are there? About 16,000. Russia and the U.S. have 93 percent of them, with more than 7,000 each; the rest are split between France, China, the U.K., Pakistan, India, Israel, and North Korea. The global stockpile is much smaller than it was at the height of the Cold War: In 1986, Russia and the U.S. had 64,000 nukes pointed at each other — enough to devastate every square inch of the entire globe. But there are growing fears that nuclear catastrophe is becoming increasingly likely.

The established nuclear powers are modernizing their arsenals with smaller, more sophisticated weapons. The unstable regime in nuclear-armed North Korea is trying to develop a hydrogen bomb. ISIS, which is richer and more ambitious than any previous terrorist group, is trying to get hold of a nuclear device. The Doomsday Clock, the symbolic countdown to Armageddon, was last year moved from five minutes to midnight to three minutes. “We are facing nuclear dangers today that are in fact more likely to erupt into a nuclear conflict than during the Cold War,” says former Secretary of Defense William Perry. READ MORE