Under the agreement, the first part of the aid — 50,000 tons of fuel oil, or an equivalent value of economic or humanitarian aid — will be provided by South Korea, Russia, China and the United States; in the case of the United States, doing so requires congressional approval, which Mr. Bush is likely to have a difficult time securing.

Image The North Korean delegation to the six-party negotiations in Beijing, led by Kim Kye-gwan, center, applauded after the agreements details were announced during closing ceremonies. Credit... Pool photo by Andrew Wong

In return for disabling the reactor and declaring all its nuclear programs, the North is to eventually receive another 950,000 tons of oil in stages. Further negotiations among the six nations are scheduled to begin on March 19 in Beijing.

“It’s about actions for actions,” Gordon Johndroe, a spokesman for the National Security Council, said this morning. “We have leverage because they’re under a U.N. Security Council sanctions regime.”

The agreement was read aloud this morning to all the delegates, gathered in a conference room at a Chinese state guesthouse in Beijing. The Chinese envoy, Wu Dawei, then asked if there were any objections. When none were made, the officials all stood and applauded.

Though Mr. Hill and other envoys spoke to reporters about the accord as soon as it had been reached, in the small hours of this morning, the formal announcement was not made by China, host of the talks, until this afternoon. During a ceremony televised nationally, the chief Chinese negotiator, Wu Dawei, praised the participating nations for their flexibility and declared the deal a “successful ending.”

Negotiators spent five days trying to reach a deal but were stymied until the very end by North Korean demands for large amounts of energy aid. Mr. Hill said he and the North Korean envoy, Kim Kye-gwan, had initially agreed at an informal January meeting in Berlin that the amount of energy promised to the North would not be specified until working groups were established. But the North insisted at the neijing talks that a hard figure be set in the new agreement.

Ultimately, the delegations agreed on 1 million tons of fuel oil. But the pil will not all come right away: After the first 50,000 tons are delivered in the initial 60-day period, the remainder will be tied delivered as the North meets later requirements to disclose and disable its nuclear arsenal.