Ship movements signal possible N.Korea missile test

North Korea usually orders its vessels to stay out of Yellow Sea waters off its west coast when it conducts short-range missile tests. China is the closest thing the North can claim as a major ally and is the impoverished state's biggest benefactor.

"The (Chinese) fishing boats have disappeared, but no other unusual moves have yet been detected," said an official with South Korea's Joint Chiefs of Staff who asked not to be named. The official would not comment on a possible missile test.

During its last test launch of short-range missiles in that area in October 2008, the North issued a no-sail order to its ships a few days before firing off missiles, South Korean government officials have said.