Secretary of State Condoleezza Rice said on Friday the United States was committed to "keeping doors open" so North Korea could return to six-party nuclear talks but would not alter its negotiating proposal as an incentive to make that happen.
Flying to Beijing to start a six-day Asian tour, Rice said President George W. Bush had set no deadline for reviving the talks, which include the two Koreas, China, Japan, Russia and the United States and which have been stalled since last June.
She expressed confidence that despite differences over currency rates and China's military buildup, the two major powers would continue to cooperate on persuading Pyongyang to abandon its nuclear weapons programs.
Rice told reporters on her plane from Washington that she aimed to capitalise on recent weeks of intensive diplomacy over North Korea, in effect tying herself more personally than before to its success or failure.
"There's a lot of activity and sometimes all that activity comes to nought. But often all that activity if channelled can produce an outcome and I wanted to come out and give the best chance ... to try to produce an outcome," she said.
"We're very focused on how to make this work. There isn't any deadline, as the president has said, no timetable about what to do next. We're going to really try to focus and take stock of where we are (with the six-party talks) and see if we can make this work," she said. Another round of talks, if held, must produce results, she said.
US officials say Pyongyang may have eight or more nuclear weapons, up from one or two at the start of Bush's term, and consider the reclusive communist state a major threat to regional and US security.
After meeting Chinese President Hu Jintao and other senior officials in Beijing on Sunday, Rice will visit Thailand, Japan and South Korea.