Stephen Bosworth, in Tokyo to brief Japanese Foreign Minister Katsuya Okada about his three-day meeting with North Korean officials this past week, said the situation remained "difficult" and members of stalled disarmament talks should stick together to make a breakthrough.
Bosworth, who had briefed officials in South Korea and China in earlier stopovers, called his Pyongyang visit "very businesslike, very candid, forward-looking." But he said how and when the six-nation negotiations would resume is yet to be resolved.
"We shouldn't expect things to start moving dramatically because of the latest development," Okada told reporters after meeting with Bosworth. "We still need to be patient."
North Korea walked away from the talks - which involve the two Koreas, China, Japan, the U.S. and Russia
- earlier this year following international criticism of its ambitions to develop long-range rocket technology. It vowed never to return.
It conducted a nuclear test in April and restarted its nuclear facilities, drawing widespread condemnation and tighter U.N. sanctions. North Korea called it an issue between itself and the U.S. and demanded bilateral talks.
After Bosworth's visit, North Korea stopped short Friday of making a firm commitment to return to the negotiating table, but its reaction raised hopes that the disarmament process could resume.
The North said it understood the need to resume the nuclear negotiations and would work with Washington to resolve remaining "differences."
"This may be the time to exercise strategic patience," Bosworth told reporters in Beijing earlier Saturday. "Everyone, including North Korea, may need to sit quietly for a bit and see what happens."
Bosworth's talks were the Obama administration's first high-level contact with North Korea. He said after leaving the North on Thursday that the two sides reached a "common understanding" on the need to restart the nuclear negotiations.