Christopher Hill told reporters after meeting his South Korean and Japanese counterparts that they would recommend a few possible dates to China, which has hosted previous talks and is the communist North's closest ally.
"We proposed a couple of dates. Everyone has a busy calendar in December but I think we'll find something and we look forward to having the Chinese set the date very soon," he said.
"I think we had pretty good agreement on how to approach the round which we really want to be substantive and successful."
The trilateral meeting took place on the sidelines of the annual week-long gathering of the Asia-Pacific Economic Cooperation (APEC) forum, at which the North Korean nuclear crisis is a key issue.
The gathering comes less than two weeks after North Korea agreed in secret negotiations in Beijing to return to the six-nation talks, which involve the two Koreas, China, Japan, Russia and the United States.
Hill, who arrived late Tuesday in the Vietnamese capital, held talks with South Korea's Chung Yung-Woo at a Hanoi hotel, before going into a three-way meeting that also included Japanese negotiator Kenichiro Sasae.
"I think we are making good progress," said Chung, who later held his own bilateral meeting with Sasae.
The six-party talks, stalled since last year, are aimed at convincing the Stalinist regime to abandon its nuclear ambitions, which were put on display last month when the North stunned the world with its first atom bomb test.
The October 9 test triggered the imposition of UN sanctions against the North, the only one of the six nations involved in the disarmament talks that is not a member of APEC.
The US negotiator said there was "great harmony" among the five nations as to how to handle the North Korean crisis.
When asked why envoys from China and Russia had not met the other three negotiators in Hanoi on Wednesday, a Japanese official said the five nations did not want Pyongyang to feel they were "ganging up" on the regime.
"The final objective is not to antagonise North Korea, but for them to abandon their nuclear program," he said.
Hill, asked if the talks could resume later this month, replied: "We're here for another few days so I think it would be difficult in November, but it's not to be excluded. But I guess that December is more realistic."
"We all feel the process really needs to show progress and this is why we need to plan this next round very carefully."
South Korea's Chung agreed that careful planning, not the precise date, was the key to making the negotiations a success.
"Timing is not an issue now that North Korea has decided to return to the talks. The question is how will we prepare for a successful meeting," he said.
APEC leaders are to express "strong support for a diplomatic solution" to the crisis and "concern" over Pyongyang's weapons test, according to a draft joint communiqué obtained Wednesday by AFP.
The leaders will call for quick implementation of a September 2005 agreement under which the North agreed to scrap its nuclear program in exchange for energy and economic aid, and a quick resumption of the six-party talks.
The Japanese official said APEC leaders were unlikely to issue a separate statement on North Korea, which would be seen as a more direct expression of concern than references to the crisis in a final joint communiqué.
"APEC is not a framework to have such a statement," he told AFP.

Copyright AFP (Agence France-Presse), 2006