As the second day of nuclear disarmament talks began here in Beijing, Chinese Vice Foreign Minister Wu Dawei called on all participants to use their "utmost political courage" to achieve progress.

The talks, aimed at ending North Korea's nuclear weapons programs, opened Tuesday with several delegates expressing a sense of purpose.

North Korea said it is prepared to work toward denuclearization, while the United States said it would take corresponding measures in return.

But both Washington and Pyongyang want the other to make the first move. Christopher Hill, the lead U.S. delegate, said the North Koreans have expressed concern about the sequence of events. "They do not want to have obligations ahead of other people's obligations," he said.

Chinese officials say there are "hard issues" on the agenda this time, unlike at the first three rounds of talks, which ended inconclusively.

North Korea demands energy aid, security guarantees and diplomatic recognition from the United States in exchange for disarmament. Washington wants North Korea to verifiably and irreversibly end its nuclear weapons programs before Pyongyang receives any incentives.

South Korea has separately offered to supply all of the North's electricity needs if the North abandons its nuclear programs. North Korea has yet to respond to that offer.

Ralph Cossa, a North Korea expert with the U.S.-based Center for Strategic and International Studies, agrees that it will be a question of which side moves first. "I don't think the U.S. will buy into normalizing relations in advance of denuclearization. I think one has to come before the other," he said.

Mr. Cossa said real progress in the talks is still anything but a certainty. "I would expect the North Koreans would now be prepared to put something on the table. The question is whether or not they will make a quote strategic decision, unquote, to commit to ending their nuclear weapons programs, or whether they'll throw [in] pre-conditions," he said.

Diplomats here do not expect a final settlement in this fourth round of talks, which resumed after a 13-month-long boycott by North Korea.