The correct answer is Containment.
Containment, also called global containment, was a foreign policy adopted by the United States towards the Soviet Union during the first years of the Cold War. The goal of this policy was to defeat the Soviet Union by avoiding the expansion of Communism and the Soviet influence over other countries and regimes.
In the image, we can see one of the main postulates of this policy, which states the domino effect theory, according to which allowing a regional state to start a revolutionary process towards socialism would eventually make the entire region fall into Communism. This domino effect process is what happened in Asia after the Chinese Communist Revolution in 1949, which was followed by the emergence of Communism in Korea, Vietnam, and Laos during the 50s, threatening entire South-East Asia and, therefore, almost all of Asia.