NBC News carried a report that the North Korean military has informed China that it plans to conduct a series of underground nuclear tests, AFP reported. The US news network cited unnamed US officials in its report. Earlier, a US intelligence official speaking on condition of anonymity told AFP that North Korea could conduct a test "with little or no warning," but a decision to do so would be "as much political as it is technical." Activity detected at potential North Korean test sites may mean a second nuclear test is being prepared but not necessarily evidence that the test is imminent, the official said. International pressure mounted Wednesday on North Korea not to conduct a second nuclear test after Pyongyang said UN sanctions imposed after its first test on October 9 were tantamount to a "declaration of war."