But a boosted atomic bomb has nowhere near the destructive power of a hydrogen bomb, and it is not considered a thermonuclear weapon. Here is the energy released by two large hydrogen bombs.

It is possible that North Korea tested a boosted atomic bomb, a weapon whose destructive power is increased by injecting tritium, a radioactive form of hydrogen. This would be an advance in the country’s nuclear capabilities.

But the yield, or total energy released by the weapon, was close to that of North Korea’s previous three tests of atomic bombs, which are simpler.

What Experts Say Was Tested

An atomic bomb works by compressing a core of uranium or plutonium until nuclei in the core split, causing an enormous explosion. A boosted atomic bomb is similar, but a tiny amount of tritium at the core makes the weapon more destructive. North Korea could have tested either of these types of bombs on Wednesday.