The island was the where Chiang Kai Shek's Nationalist forces retreated to once Mao Zedong and the communists took control of the mainland. Taiwan was protected by Communist invasion by the United States Navy. On March 3, 1955, the United States and the Republic of China signed the Sino-American Mutual Defense Treaty which prevented mainland Chinese takeover of the island. Around this time, the ROC was recognized as the legitimate China over the PRC. This changed in the late 1960s and the 1970s when much of the international community recognized the PRC. In 1971, the ROC was replaced by the PRC in the United Nations Security Council. In 1979, the United States severed relations with Taiwan as it recognized the People's Republic of China as the legitimate government of China as per the "One-China policy." The Sino-American Mutual Defense Treaty was terminated on December 31, 1979. Despite this, the United States and most of the international community maintained unofficial relations with Taiwan. The U.S. still continued to supply the most advanced military hardware to the ROC Armed Forces, which included during the 1980s up to the 1990s including the F-16 Falcon as of the breakup of World War III. The Taiwanese were in the process of creating their own fighter jet, the ADIC FCK-1, while was in the process of ordering the French Dassault Mirage 2000.
World War III
Taiwan took a cautious role in the initial stages of the war. It partially mobilized its armed forces after reports of Soviet Air Force TU-95s that crossed nearby Taiwanese and Philippine air space. The ROC anticipated a potential Chinese invasion. Fears of the invasion finally came through in January 1990 when the People's Republic of China entered the war on the side of the Soviet Union. China declared war on the United States and its allies, which included Taiwan. For many years, analysts have predicted that the political status of Taiwan would be a flashpoint for a war in Asia. However, Taiwan had the upper hand since their navy and air force was technologically superior compared to the Chinese People's Liberation Army Navy. As predicted, the Taiwan Strait became the a battleground between Chinese and Taiwanese vessels. Taiwanese destroyers were able to sink several PLA vessels, with Taiwan's two submarines purchased from the Netherlands in 1986, the ROCS Hai Lung and the ROCS Hai Hu, became the hunters for PLA ships within the strait. They would also join American, Australian, British, and Japanese submarines attacking ships and naval yards within the Chinese coastline.