The U.S. military is reportedly tracking a North Korean ship in the Pacific Ocean that may be carrying weapons of mass destruction.

U.S. media said Friday that the U.S. is monitoring the North Korean vessel named “Kang Nam,” which left a port in North Korea on Wednesday.

The U.S. claims the ship has been involved in weapons proliferation in the past.

The Joint Chiefs of Staff chairman, Admiral Mike Mullen, did not confirm the reports during a news conference at the Pentagon on Thursday.

He only stressed that a new U.N. resolution sanctioning North Korea would allow the Navy to search a ship only after receiving permission. He noted that if a vessel refused a search, the home country of the port where the vessel docks would be required to search its cargo.

The suspected ship would be the first vessel monitored under tougher new U.N. sanctions.