SEOUL: The Democratic People's Republic of Korea (DPRK) reminded the United States yesterday that it has nuclear weapons and warned it will strike back if attacked, as a US destroyer continued to trail a DPRK cargo ship suspected of carrying illicit weapons.

The Kang Nam, previously involved in weapons shipments, is the first vessel monitored under new UN sanctions adopted after the DPRK's nuclear test last month. It could become a test case for interception of DPRK ships at sea - something Pyongyang has said it would consider an act of war.

President Barack Obama said the US is ready to cope with "any contingencies" amid reports the DPRK appears to be preparing for a long-range missile test planned sometime around July 4, the Independence Day holiday. Defense Secretary Robert Gates has ordered additional protections for Hawaii as a precaution.