A top US official says it appears North Korea has test-fired a short-range missile that landed in the Sea of Japan. White House Chief of Staff Andrew Card told US television this is not the first such incident, but said Washington is watching closely. He accused North Korea of trying to be, what he called, "bullies in the world." Japanese broadcaster NHK quotes a Japanese official as saying the missile will not pose a threat to Japan. North Korea fired a missile over Japan in 1998, and shot at least two missiles into the Sea of Japan two years ago. Such missile tests are seen as an effort by North Korea to strengthen its hand in dealings with its critics. The United States and North Korea have been locked in a standoff over Pyongyang's nuclear program. On Saturday, diplomats said the United States warned the International Atomic Energy Agency that North Korea appears ready to conduct an underground nuclear test.