The White House warned Monday that diplomatic efforts to defuse the crisis over North Korea's nuclear programs cannot "drag on forever" and urged Pyongyang to return to negotiations.
"The United States put forward a very practical proposal at the last round of talks. We want to see results to moving forward on that proposal. We want to see North Korea come back to the talks," said spokesman Scott McClellan.
His comments came after US Secretary of State Condoleezza Rice warned during a visit to China that North Korea faced "problems" if it failed to return to the talks and that Washington was looking at "other options."
At the same time, Rice stressed: "We have no intention to attack."
"Secretary Rice was saying what we've said, the time to come back to the talks is now. She expressed that this could not drag on forever; we need to resolve this issue," said McClellan.
The United States has ruled out separate bilateral discussions with North Korea outside the context of six-party talks that also group China, Japan, Russia, and South Korea.
North Korea has boycotted the six-party talks since last June, following three inconclusive rounds, and has often demanded separate, bilateral talks with Washington to resolve the standoff.
The six-party talks aim to persuade the North to give up its nuclear weapons program in exchange for diplomatic and economic benefits.
North Korea last took part in the talks in June 2004. It declared on February 10 that it has nuclear weapons and that it was indefinitely suspending its participation in the dialogue.
A senior State Department official, who spoke on condition of anonymity, expressed concern over what he called "a decided lack of movement" in the talks and difficulty in reading North Korea's intentions.
"I think we're concerned that as this drags on, the threat is not being reduced, and that gives a certain sense of urgency to what we are trying to accomplish," the official said.
But he added, "We're not yet at the point where we believe that the six-party talks is anything but the preferred way to go."