Q+A: What might happen with monitored North Korean ship?

(Reuters) - The U.S. Navy is tracking a North Korean ship under a new U.N. resolution that bars Pyongyang from trading in weapons, including missile parts and nuclear material.

U.S. officials have declined to say what the Kang Nam might be carrying, but said it was "a subject of interest." The vessel left a North Korean port on Wednesday.

WHAT IS THE LATEST?

Fox News quoted a senior U.S. military source as saying the ship appeared to be heading toward Singapore and that the navy destroyer USS John McCain was positioning itself in case it gets orders to intercept, according to a story on its website.

Singapore, a U.S. ally, said it takes "seriously the proliferation of weapons of mass destruction" and would act "appropriately" against the ship if the vessel heads to its port with a cargo of weapons. Singapore is the world's top ship refueling hub. It was unclear how long the vessel would be able to sail before it needs to refuel.

The Kang Nam is the first North Korean ship to be monitored under the new resolution, adopted this month in response to Pyongyang's May 25 nuclear test. The resolution authorized U.N. member states to inspect North Korean sea, air and land cargo.

The United States and others have said they suspect North Korea of selling arms, missile parts and proliferating nuclear expertise in violation of earlier U.N. sanctions.

HOW MIGHT THE SITUATION PLAY OUT?

A U.S. naval vessel could intercept the ship, which is believed to be North Korean flagged, while it is in international waters and officers could seek permission to board. According to the resolution, permission must be given by the flag nation, or Pyongyang in this case, which would be sure to refuse.

North Korea has not commented on the monitoring of the ship but is likely to regard any attempt to inspect its cargo as highly provocative and a further reason to test the resolve of the international community. It has threatened a military strike if any country tries to impose any sort of naval blockade.

WHAT DOES THE U.N. RESOLUTION ALLOW?

The resolution calls upon -- but does not order -- U.N. member states to inspect cargo to and from North Korea if there are reasonable grounds to believe it contains banned materials.

It calls upon member states to inspect vessels, with the consent of the flag state, on the high seas, if they have information the ship is carrying prohibited materials.

If the flag state refuses to give permission, it is supposed to ask the vessel to sail to a convenient port for inspection by local authorities, who should seize any banned goods and destroy them. However, the resolution does not authorize the use of force. If a North Korean ship refuses to be inspected, the only recourse is to report the refusal to the Security Council.

The resolution also says member states should withhold fuel and supplies to North Korean vessels if a ship is believed to contain prohibited items unless provision of such services would be needed on humanitarian grounds.

This raises the prospect of a protracted standoff in a foreign port should the North Korean vessel try to dock to refuel and the captain refuse to allow local authorities on board.