North Korea has agreed to suspend its enriched-uranium nuclear weapons program, a key United States demand for the resumption of disarmament talks, news reports said Saturday.

Yonhap news agency and the Chosun Ilbo daily quoted an unidentified diplomatic source saying the Washington had also agreed to provide the North with up to 240,000 tons of food aid.

U.S. Secretary of State Hillary Clinton won promises of further reforms from Myanmar's rulers in historic talks Thursday, but said it was too soon to end sanctions after decades of repression.

Paying the most senior U.S. visit in more than half a century to a nation long distrustful of the West, Clinton offered only cautious incentives to encourage more action, despite a call by China for Western sanctions to be lifted.

North Korea's military on Saturday threatened retaliation against "provocative" acts from the South including the scattering of anti-Pyongyang propaganda leaflets across the border.

The warning came as activists in South Korea opposed to the secretive regime plan to float balloons carrying the leaflets across the border in time for the 66th anniversary of the North's ruling communist party inauguration on Monday.

South Korea has arrested a North Korean agent who plotted to assassinate an outspoken anti-Pyongyang activist with a poison-tipped needle, the intended victim and a news report said Friday.

The agent, identified only as An, was in possession of the needle and other weapons at the time of his arrest, Yonhap news agency said.

North Korea has sent secret agents to South Korea to try to assassinate its defense minister, who has vowed a stern response to attacks from the communist state, media reports said Wednesday.

The defense ministry said it could not confirm the reports but added that security for Kim Kwan-Jin has not been strengthened recently .

The United States said Saturday it was "encouraged" by surprise talks between North and South Korea over Pyongyang's nuclear program, but remained cool on resuming disarmament talks.

U.S. Secretary of State Hillary Clinton told regional foreign ministers at an Asian security forum in Indonesia that the onus remained squarely on the North to prove its sincerity before the stalled six-party talks could resume.

U.S. and South Korean troops on Monday launched major annual land, sea and air exercises, amid North Korean threats to turn Seoul into a "sea of flames" in the event of any provocation.

The Key Resolve/Foal Eagle drills are the first of their type since the communist state's deadly shelling of a South Korean border island last November.

North Korea's military threatened Sunday to fire at South Korea, as Seoul prepared to start annual joint drills with U.S. troops — maneuvers Pyongyang says are a rehearsal for an invasion.

The North's military warned that it would shoot directly at South Korean border towns and destroy them if Seoul continued to allow activists to launch propaganda leaflets toward the communist country, Pyongyang's official Korean Central News Agency said. The warning was conveyed to South Korea's military earlier Sunday, it said.

North Korea has opened an account with the global video-sharing website YouTube, uploading clips praising the isolated communist state and denying allegations that it sank a South Korean warship.

Eleven clips were found Tuesday under the name of uriminzokkiri, a North Korean government website.

North Korea's military threatened Tuesday to retaliate against South Korea over its planned naval drills this week near their disputed sea border.

The North's official Korean Central News Agency said that the military would crush the naval drills with a powerful physical blow and warned all civilian ships to stay away from areas near the sea border.