Final answer:
U.S. foreign policy has often been driven by concerns about Communism, particularly during the Cold War, but humanitarian factors and moral considerations have also influenced decisions. The outcomes of involvement, such as in WWI, WWII, or the Vietnam War, could have differed significantly with alternative strategies, and debates over the roles and actions of the U.S. continue to be relevant today.
Step-by-step explanation:
U.S. involvement in global affairs has been shaped by various strategic, humanitarian, and ideological factors. Concerns about Communism have often been the leading concern behind America's major foreign policy decisions, particularly during the Cold War. This focus on containment was demonstrated in the U.S. response to the Vietnam War, where the battleground tactics of traditional warfare were rendered ineffective in jungle guerilla warfare conditions. Moreover, moral considerations also played a role, as seen in debates over the appropriate response to the Holocaust and in the consideration of whether to use atomic weapons in Japan, where issues of race and the brutality of war crimes against U.S. troops influenced decision-making.
Reflecting on the hypothetical scenarios such as the U.S. not participating in WWI or expanding the Korean War into China reveals the complexities that could have led to radically different outcomes, both domestically and internationally. The U.S. has also faced criticism and reevaluation of its policies following events like the My Lai Massacre in Vietnam and the limited response to Japanese aggression in the 1930s.
The question of whether the United States should act as a 'world police' or intervene in international crises remains divisive, with opinions shaped by historical precedents and current global dynamics. Ultimately, the degree to which the U.S. could have been more or less involved in historical events depends on a variety of factors, including military strategy, geopolitical considerations, human rights concerns, and public opinion at the time.