North Korea claimed that a nuclear blast on Sunday was a big advance from its previous five tests because it had successfully detonated a hydrogen bomb. But some experts suspect the North may have tested a “boosted” atomic bomb.

How are a hydrogen bomb and a regular atomic bomb different? And why would that matter to the United States and its allies? Here’s what the experts say.

How do nuclear weapons work?

Nuclear weapons trigger an explosive reaction that shears off destructive energy locked inside the bomb’s atomic materials.