The First Taiwan Strait Crisis occurred between 1954 and 1955, primarily involving the People's Republic of China (PRC) and the Republic of China (ROC) on Taiwan. Tensions escalated when the PRC bombarded the offshore islands of Kinmen and Matsu, which were controlled by the ROC. The United States, supporting the ROC, responded by reinforcing its military presence in the region and issuing a mutual defense treaty with Taiwan. The crisis highlighted the ongoing conflict between the PRC and ROC following the Chinese Civil War. It ended with a ceasefire, but the underlying issues remained unresolved, setting the stage for future confrontations in the Taiwan Strait.