The U.S. Navy is currently following a North Korean ship suspected of carrying weapons in violation of the resolution, but Pentagon press secretary Geoff Morrell said Wednesday that the U.S. and its allies have not decided whether to contact and request an inspection of the ship.

The Kang Nam left the North Korean port of Nampo a week ago and is believed bound for Myanmar, South Korean and U.S. officials have said. A senior U.S. defense official said Wednesday that the ship had already cleared the Taiwan Strait.

Another U.S. defense official said he tended to doubt reports that the Kang Nam was carrying nuclear-related equipment, saying the information officials had received seemed to indicate the cargo was conventional munitions.

The U.S. officials spoke on condition of anonymity because they were discussing intelligence.

Adding to the tensions, anticipation is mounting that the North might test-fire short- or mid-range missiles in the coming days. The North has designated a no-sail zone off its east coast from June 25 to July 10 for military drills.

A senior South Korean government official said the ban is believed connected to North Korean plans to fire short- or mid-range missiles. He spoke on condition of anonymity, citing department policy.

The North has also been holding two U.S. journalists since March. The reporters, Laura Ling and Euna Lee, were sentenced to 12 years of hard labor for illegal border crossing and hostile acts earlier this month.

Ling's husband, Iain Clayton, said Wednesday that his wife called him on Sunday night and she sounded scared. He also said Ling's medical condition has deteriorated and Lee has developed a medical problem. Ling reportedly suffers from an ulcer.

Associated Press writers Hyung-jin Kim in Seoul and Pauline Jelinek, Pamela Hess and Lolita Baldor in Washington contributed to this report.