On Wednesday, North Korea claimed that it had tested a hydrogen bomb, bringing to four the number of nuclear weapons it has set off on its own territory since 2006. The act drew international condemnation, prompting us to ask: What’s different this time? Does condemnation of the test from China, North Korea’s greatest ally, matter? Shouldn’t the U.S. and China, or China and South Korea, or China and Japan, use nuclear disarmament on the Korean Peninsula as an issue over which to stand united?