US Navy is tracking several North Korean ships

“We have been interested in this one ship [the Kang Nam], but we’ve been interested in, frankly, multiple ships,”

It's a good thing that President Obama has ordered the US Navy not to use force to inspect the North Korean ships.

"The U.N. resolution lays out a regime that has a very clear set of steps," Flournoy said, according to the Yonhap news agency. "I want to be very clear ... This is not a resolution that sponsors, that authorizes use of force for interdiction."

So the national security of the USA is now dependent on half assed UN resolutions. There is a possibility that at least one of these North Korean ships could be carryinng nuclear, chemical or even biological weapons and we can't use force to find out. Insanity.
Joong Ang Daily

The United States said it was monitoring “multiple” North Korean ships suspected of carrying weapons and that it would discuss with its allies what to do with one suspect vessel it is tracking.

While the United States has been tracking the Kang Nam since last week, the Pentagon said it is closely monitoring several other North Korean ships allegedly carrying weapons. “We have been interested in this one ship [the Kang Nam], but we’ve been interested in, frankly, multiple ships,” Pentagon press secretary Geoff Morrell said.[...]

Morrell said U.S. authorities were monitoring North Korean ships even before the UN Security Council resolution and were doing so under the Proliferation Security Initiative. Created in 2003, the PSI is a multinational regime designed to halt the proliferation of weapons of mass destruction by interdicting and inspecting suspect cargo in territorial waters of 95 PSI members.

“Under PSI, we had obligations to and an interest in tracking ships to make sure there was no proliferation of any banned goods,” Morrell said. “We obviously, under [Resolution] 1874, have additional responsibilities and authorities, and we appreciate that.”