North Korea's powerful ally China has welcomed Pyongyang's agreement to freeze its nuclear activities in return for massive food aid from the United States.
Also on Thursday, South Korea and Japan hailed North Korea's commitment to suspend its uranium enrichment programme along with nuclear and long-range missile tests, and to let United Nations nuclear inspectors monitor the deal.
The deal, coming months after the death last December of longtime leader Kim Jong-Il, raised cautious hopes of eased tensions under Kim Jong-un, North Korea's new young leader.
It could also boost Kim's prestige in the run-up to a major celebration next month, marking 100 years since the birth of the Kim dynasty's late founding leader Kim Il-sung.
The breakthrough followed US-North Korean talks in Beijing last week, the first under the new regime.
China is North Korea's sole major ally and economic prop, and said it would help push forward the six-party negotiations on nuclear disarmament which bring together the United States, the Koreas, China, Russia and Japan.
"China is willing to work with relevant parties to continue to push forward the six-party talks process, and play a constructive role to realise long-term peace and stability on the Korean peninsula and northeast Asia," said foreign ministry spokesman Hong Lei.
The nuclear disarmament talks have been stalled for some three years, although all six parties have been talking for months about ways to revive them.
The disclosure in November 2010 of the enrichment programme, which could give the North a second path to an atomic bomb, lent urgency to the diplomacy.
South Korea, whose relations with its neighbour have remained icy under the new leadership, also backed the agreement disclosed simultaneously by the US and North Korea on Wednesday night.
Russia's foreign ministry welcomed the moratorium on nuclear testing and uranium enrichment.
Koichiro Gemba, Japan's foreign minister, said the deal was "an important step" but called for concrete action. Tokyo still wants "the complete and verifiable denuclearisation of the Korean peninsula", he said.
The US state department was cautious in its response, but said Washington was ready to finalise details of a proposed food aid package of 240,000 metric tonnes of nutritional assistance.
It said more aid could be agreed upon based on continued need.
"The United States still has profound concerns regarding North Korean behaviour across a wide range of areas, but today's announcement reflects important, if limited, progress in addressing some of these," a state department statement said.
|Secret talks that led to the agreement were held at the North Korean embassy in Beijing [AFP]
A South Korean foreign ministry spokesman said the development reflected "the close work Seoul and Washington have done to try to resolve the nuclear standoff", while the International Atomic Energy Agency called it "an important step forward".
Al Jazeera's Kimberly Halkett, reporting from Washington DC, said that its linking "nutritional assistance" with political developments was contrary to standard US foreign policy.
"[This move] is certainly going to come under the microscope in terms of US policy. The US has used [food aid] successfully as leverage and there is going to be some talk about that," she said.
The announcement comes as the administration of Barack Obama, the US president, steps up pressure on Iran over its atomic ambitions, which Western governments fear are aimed at producing nuclear weapons.
Christopher Hill, the former chief US negotiator in the six-party talks, said it was an important step that Kim Jong-un had made such a high-profile decision in the wake of his father's death.
He said that the military, which is influenced by Chang Song-taek, Kim Jong-il's powerful brother in law, had probably played a role in the agreement.
"I think the first order of business is to try to figure out the terms by which we provide the food aid," Hill said. "We're going to have to make sure the North Koreans have the aid and that we can monitor that the food aid goes to the right people."
North Korea agreed to curtail its nuclear activities under an aid-for-denuclearisation agreement reached in September 2005 by the six-parties.
Under the terms of that deal, the North agreed to abandon its nuclear programmes in exchange for economic and diplomatic incentives to be provided by the other parties involved in the negotiations.
But the embryonic deal was never fully implemented.
Instead, the North held two nuclear bomb tests, in 2006 and 2009, and later disclosed a uranium enrichment programme, giving it a second path to obtaining fissile material for bombs, in addition to its long-standing programme of producing plutonium.
The US, South Korea and their allies had been sceptical of North Korea's assertions that it stands ready to return to the six-party talks, and said they would insist on evidence of the country's willingness to denuclearise before any such talks could resume.