Final answer:
The expansion of U.S. overseas commitments after World War II responded to the perceived Soviet threat and the need for active engagement in a transformed global landscape. The United States aimed to contain communism by supporting democracies and forming strategic alliances. The Cold War justified these actions to some extent, as each side saw the other as a threat to its way of life and security.
Step-by-step explanation:
The expansion of U.S. overseas commitments after World War II was a strategic response to shifting global dynamics and the perceived threat of Soviet communism. The bipolar power structure of the post-war world and the weakening of former global powers necessitated a departure from the United States' traditional isolationist stance. The American policy of active engagement was aimed at containing the spread of communism and involved supporting democratic governments, aiding in economic recovery, and forming strategic alliances.
Western leaders were concerned about the spread of communism because it threatened the political and economic systems of the West. The Soviet Union's expansionist aims were driven by the desire to propagate their communist ideology and to establish a buffer against potential threats, which justified the U.S.'s bolstering of its overseas commitments to some extent. The fear of global domination by the opposing side led to a protracted ideological, political, and military struggle known as the Cold War.
The Truman Doctrine and policies like NSC-68 emphasized American commitment to countering Soviet influence globally. This expansion of commitments included economic assistance through plans like the Marshall Plan, military aid to countries resisting communist insurgencies, and a readiness to use nuclear weapons as a crucial part of defense policy under the Eisenhower administration. Ultimately, this represented a fundamental shift from isolationism to global engagement as a means of navigating the new world order and protecting perceived American and allied interests.