A North Korean ship being tracked by the U.S. Navy on suspicion of carrying illicit weapons has reportedly changed course.

U.S. media quoted two unnamed American government officials as saying that the Kang Nam on Sunday suddenly reversed direction and started sailing northward after having traveled south and southwest for more than a week.

Media reports said it is uncertain where the Kang Nam is going or whether its cargo includes materials banned by a new U.N. resolution. The reports said the ship is currently sailing in waters some 160 kilometers off Vietnam.

According to the U.S. officials, the Kang Nam had been moving very slowly in recent days, which could signal attempts to conserve fuel.

The media speculated that the Kang Nam suddenly changed course after the Myanmar government notified the ship that it will refuse docking permission if it is found to be carrying banned materials.

While acknowledging that the Kang Nam's destination was unclear, some U.S. officials said last week that it could be going to Myanmar.

The Aegis-equipped destroyer, USS John S. McCain, has been tailing the North Korean ship since it left the North Korean port of Nampo on June 17th.

The Kang Nam is the first vessel monitored under new U.N. sanctions that ban Pyongyang from selling arms and nuclear-related material.