Russia is scrapping its ratification of a key nuclear test ban. Here's what that means
The world's major nuclear powers haven't tested a bomb this century, but experts worry that may be about to change.
nuclear test monitoring
A nuclear-test monitor calls Tonga volcano blast 'biggest thing that we've ever seen'
A station to detect nuclear weapons tests picked up the volcanic eruption in Tonga from Antarctica. Some experts say the blast could be more than 50 megatons, while NASA estimates 6-10 megatons.