WASHINGTON: A North Korean ship suspected of carrying weapons has reversed course after being tracked by the U.S. Navy under a new U.N. monitoring program, a U.S. official said on Tuesday.

The official, speaking on condition of anonymity, confirmed the Kang Nam was heading back in the direction of North Korea after turning around within the last few days.

"We've no idea where it's going," the official said. "The U.S. didn't do anything to make it turn around."

"It's pretty much on a reciprocal track," the official added.

South Korean media reports have said the ship, a known North Korean weapons trader, was probably heading for Myanmar, while other media outlets have named Singapore as a possible destination. Singapore's government has said it will take action if the ship tries to dock with a cargo of weapons.

North Korea has defied the international community with a series of nuclear and missile tests, raising fears of a spread of nuclear weapons to countries such as Iran.

U.S. officials have not said why the Navy is monitoring the Kang Nam but the New York Times reported on Tuesday some senior members of the Obama administration are wondering whether they are being manipulated by North Korean leader Kim Jong-il.

"The whole thing just doesn't add up," the newspaper quoted one senior administration official as saying.

"My worry is that we make a big demand about seeing the cargo, and then there's a tense standoff, and when it's all over we discover that old man Kim set us up to look like George Bush searching for nonexistent (weapons of mass destruction)."

The Kang Nam is the first North Korean ship monitored under a U.N. security resolution that bars Pyongyang from exporting weapons including missile parts and nuclear materials.

The ship, which left North Korea in mid-June, has been tracked by several U.S. Navy vessels over the course of its journey and now was being monitored by a U.S. Navy destroyer, the official said.

Speaking before news of the ship's reversal, the chief of U.S. Naval Operations, Admiral Gary Roughead, said he thought the U.N. resolution had increased pressure on Pyongyang and was proving to be an effective tool against proliferation.

"It gets pretty lonely out there when you have only so much water and only so much gas," Roughead said, referring to a ship with no safe harbor.