North Korea launches four short-range missiles

North Korea has conducted test-launches of four short-range missiles, the latest in a series of recent provocations that included the nation's second underground nuclear blast.  "North Korea has conducted two nuclear tests, but it isn't thought to have designed a nuclear warhead that could be delivered by a missile. Such a first-generation plutonium warhead could have a mass of 1,000 kilograms or more," according to Massachusetts Institute of Technology professor Theodore Postol and physicist David Wright of the Union of Concerned Scientists, both Ploughshares grantees, in the Bulletin of the Atomic Scientists.

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