Ever since Nationalist forces retreated to Taiwan in 1949, the island has been confronted with the permanent risk of Communist invasion . In the 1950s the People's Liberation Army (PLA) launched two attacks against the last bulwark of Chiang Kai-shek 's regime. The last major crisis in the Taiwan Strait dates back to the mid-1990s, when the People's Republic of China (PRC) conducted missile "tests" dangerously close to Taiwan's shores. This display of military strength was aimed at then-President of Taiwan Lee Teng-hui, who had publicly refuted Beijing's territorial claims on the island.