North Korea has threatened to attack Washington with a nuclear weapon but it isn't thought to be able to mount a nuclear weapon on a missile yet, or to be able to hit the mainland U.S. with a missile.

WSJ: North Korea to Restart Yongbyon Nuclear Plant

South Korea's military doesn't believe North Korea has a nuclear weapon small enough to mount on a missile, a defense ministry spokesman said Friday.

WSJ: Korean Nuclear Worries Raised

U.S. intelligence officials have said they do not believe Iran has decided to develop a nuclear weapon, even as evidence continues to mount that the country is improving its ability to do so.

CNN: STORY HIGHLIGHTS