North Korea has announced it is cancelling its nonaggression pact and emergency hotline with rival South Korea.
The announcement came hours after the United Nations Security Council adopted new sanctions against North Korea in response to the North’s third nuclear test on February 12.
A statement issued by North Korea’s Committee for the Peaceful Reunification of Korea said the North was abrogating "all agreements on nonaggression" with U.S.-backed South Korea.
The statement, carried by the official Korean Central News Agency, said Pyongyang was also cutting immediately the North-South communications hot line.
North Korea earlier this week threatened to revoke the armistice that ended the 1950-53 Korean War.
South Korean President Park Geun-hye on March 8 voiced concern over the security situation.
"Our current security situation is very grave. North Korea is threatening us with a nuclear test and long-range missile development. They are also threatening us, saying they would nullify the armistice agreement," Park said.
China, North Korea's sole major ally, called for "calm and restraint."
Beijing says it wants "full implementation" of the new UN Security Council resolution.
China has also called for a return to the six-party talks that bring together the United States, North and South Korea, Japan, Russia, and China. The talks have been stalled since 2009.
German Foreign Minister Guido Westerwelle, meanwhile, called on China to use its influence on North Korea to persuade Pyongyang to stop its "threats and provocations."
On March 7, North Korea threatened a preemptive nuclear strike against the United States.
The White House responded by saying it was confident the U.S. could defend itself from a North Korean ballistic-missile attack.
Based on reporting by AP, AFP, and dpa