Updated at 11:44 a.m. ET: WASHINGTON -- North Korea agreed on Wednesday to stop nuclear tests, uranium enrichment and long-range missile launches and to allow nuclear inspectors to visit its Yongbyon nuclear complex to verify the moratorium has been enforced.

The announcement, made simultaneously by the U.S. State Department and North Korea's official news agency, paves the way for the possible resumption of six-party disarmament negotiations with Pyongyang and follows talks between U.S. and North Korean diplomats in Beijing last week.

It also marks a significant policy shift by North Korea's reclusive leadership following the death in December of veteran leader Kim Jong-il.

Secretary Hillary Rodham Clinton told a Senate hearing that North Korea's suspension of nuclear activities a "modest first step" but also "a reminder that the world is transforming around us."

N. Korea envoy: 'Positive' signs from talks with US

The U.S. still had reservations about North Korea, the State Department said in a statement.

"The United States still has profound concerns regarding North Korean behavior across a wide range of areas, but today’s announcement reflects important, if limited, progress in addressing some of these," it read.

It said Washington reaffirmed that it did not have hostile intentions toward North Korea and was prepared to take steps to improve bilateral ties and increase people-to-people exchanges.

An unidentified spokesman from North Korea's Foreign Ministry said in its statement carried by the state-run news agency that the North agreed to the nuclear moratoriums and the allowance of U.N. inspectors "with a view to maintaining positive atmosphere" for the U.S.-North Korea talks.

'Nutritional assistance'
Clinton also said the U.S. will meet with North Korea to finalize details for a proposed package of 240,000 metric tons of food aid, referring to it as "nutritional assistance." She said intensive monitoring of the aid would be required.

North Korea appealed for food aid a year ago to alleviate chronic shortages.

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The surprise announcement was a step forward for Washington's campaign to rein in renegade nuclear programs around the world and comes as the Obama administration steps up pressure on Iran over its atomic ambitions, which western governments fear are aimed at producing nuclear weapons.

Since 2006 North Korea has tested missiles, staged two nuclear tests and unveiled a uranium enrichment program that could give it a second route to manufacture nuclear weapons, in addition to its existing plutonium-based program. At low levels, uranium can be used in power reactors, but at higher levels it can be used in nuclear bombs.

The U.S. still has nearly 30,000 troops based in South Korea, a legacy of the 1950-53 Korean War, that ended in a armistice rather than a peace treaty.

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Msnbc.com stadd, The Associated Press and Reuters contributed to this report.