Hydrogen bomb

Nuclear physicist Grigory Klinishov was co-creator of the Soviet Union's first two-stage hydrogen bomb.

A number of islands had to be evacuated after a 1954 U.S. nuclear weapons test.

The VA would not comment on the case.

South Korean and Chinese scientists worry that a collapse at the mountain could trigger a radiation leak.

Crowds lined up to cheer the scientists as they paraded around Pyongyang.

Seoul fears Pyongyang will soon fire an intercontinental ballistic missile toward the North Pacific.

The U.S. president said Pyongyang's latest test was an "embarrassment" to China and urged Seoul to abandon its attempts at diplomacy with Kim Jong Un.

Hydrogen bombs have never been used in warfare and can generate force hundreds of times higher than the atomic bombs used at Hiroshima and Nagasaki.

Pyongyang carried out its sixth and most powerful nuclear test on Sunday, causing a 6.3 magnitude earthquake.

This year, the country has carried out 10 missile tests troubling neighboring countries.

Park Geun-hye also said the North is "merciless" and under an "extreme reign of terror."

North Korea's nuclear weapons program is expanding—and China won't do much about it.

Experts have dismissed the registered seismic activity as too low a magnitude for a hydrogen bomb.

The U.S. is targeting fewer North Korean entities than those of Burma, Cuba, Iran and Zimbabwe.

Pyongyang has tested something, but it's unlikely to be a full-blown H-bomb.