North Korea, citing what it said was U.S.-led moves to punish it for its recent nuclear testing, threatened Tuesday to nullify the Korean war truce. The North also denounced joint South Korean-U.S. military exercises scheduled to begin Monday, saying if the drills are conducted, it will sever military phone links across the border with South Korea, Yonhap News Agency reported. The \"Key Resolve\" program of two weeks of military exercises is expected to involve 10,000 South Korean troops and 3,500 U.S. troops. The Korean People\'s Army, said it would carry out more and stronger countermeasures in response to the \"hostile\" policies of the United States and South Korea, an army spokesman said on North Korean state television. North Korean leaders decided Monday to halt the work of its delegation at Panmunjom, where North and South Korean delegates typically meet for communication and negotiations, Xinhua reported. A Chinese Foreign Ministry spokeswoman said Tuesday Beijing expected all parties \"to do more to ease tensions on the peninsula and promote regional peace and stability.\" North Korea conducted its third nuclear test Feb. 12, drawing international condemnation. The United States and some other countries were urging the U.N. Security Council to impose stricter sanctions on North Korea because of the testing.