evidence: The ongoing dispute has led to heightened military confrontation in the Taiwan Strait, which geographically separates mainland China from the island of Taiwan. In the First Taiwan Strait Crisis of 1954–55, the PRC shelled the Kinmen and Matsu islands, situated close to the mainland, in an unsuccessful attempt to deter the United States from signing a mutual defense treaty with the Nationalist government. Following the First Taiwan Strait Crisis, Taipei and Beijing reached a tacit understanding of a "median line," also called the center line, to guide rules of engagement and prevent miscalculation in the Taiwan Strait. The PRC repeated its artillery bombardment of Kinmen in 1958 during the Second Taiwan Strait Crisis. In response, the United States drew up plans for a nuclear strike on mainland China, demonstrating the Dwight Eisenhower administration’s Cold War commitment to Taiwan. The PRC fired live ammunition and missiles into Taiwan’s waters during the Third Taiwan Strait Crisis of 1995–96 to express disapproval of Taiwanese President Lee Teng-hui’s visit to the United States.