North Korea claimed Tuesday that it has successfully weaponized more plutonium for atomic bombs, a day after warning Washington to agree quickly to direct talks or face the prospect of a growing North Korean nuclear arsenal. The announcement underlined Pyongyang's impatience over securing one-on-one talks with Washington, as well as the difficulties in dealing with a regime that resorts to threats and provocations to get what it wants. Pyongyang's official Korean Central News Agency said North Korea had finished reprocessing 8,000 spent nuclear fuel rods, which experts say would provide enough weapons-grade plutonium for at least one more nuclear bomb. The claim may not mean much, since North Korea is believed to already have enough...