The United States has threatened to freeze North Korean assets if it does not toe the line in talks aimed at ending its nuclear weapons programme.
Chief US negotiator Christopher Hill That is a light-water reactor. So indeed we have a problem
US Secretary of State Condoleezza Rice said the United States was not solely dependent on the six-party talks, deadlocked in Beijing, to get North Korea to abandon its nuclear ambitions.
"We're not sitting still, you know, we're working on anti-proliferation measures that help to protect us," Ms Rice said in an interview conducted yesterday with the New York Post.
"The president signed an executive order, if you remember that freezes assets and some entities that we believe that are engaging in proliferation trade," she said.
The talks are in disarray after Pyongyang insisted on being supplied a light-water nuclear reactor. Pyongyang had also threatened to boost nuclear weapons production if it was not given the reactor, reports said.
Chief US negotiator Christopher Hill said: "Just in the last couple of days, they've come back with a whole new concept. That is a light-water reactor. So indeed we have a problem."
The United States said the North's demand held up a deal that would allow aid and security guarantees and Japan, and it urged the North to think again.
Failure to reach an accord at the Beijing talks could prompt Washington to take the issue to the UN Security Council and press for sanctions. China opposes such a move, and North Korea has said sanctions would be tantamount to war.