An unofficial delegation of U.S. experts visiting North Korea last week examined what the Pyongyang government said was its “nuclear deterrent,” apparently providing the first confirmation that Pyongyang has produced the key ingredient for nuclear weapons. U.S. officials said they have received only initial details of the visit, and they cautioned that they do not yet know the full extent of the facilities and materials examined by the delegation. But one official said the delegation had been shown what the North Koreans described as recently reprocessed plutonium. Full Story