When communism spread into China, how did that increase cold war tensions?

The year 1949 proved pivotal in changing the dynamics of post-World War II international relations. In October 1949, the People’s Republic of China(PRC) replaced the Republic of China (ROC) after the Chinese Communists won a nationwide victory in the civil war and drove the Nationalist government to Taiwan. The collapse of the Nationalist cause shocked the American public, which had idealized “free China” as a democratic ally and valiant protégé. Now, a Communist China, comprising a quarter of the world’s population, had inevitably extended the Cold War to East Asia. The PRC’s foreign policy during the Cold War went through several distinctive stages.