The U.S. role in world affairs has been hotly debated since the country’s inception in the late 18th Century.
For much of U.S. history, strong tendencies toward isolationism prevailed among American policymakers. A reluctance to engage in foreign alliances, in particular, was prevalent until World War II and the post-war creation of the North Atlantic Alliance. The Cold War requirements for a vastly expanded role in world affairs cemented the U.S. position as a world power, validated by the country’s unparalleled capabilities for projecting substantive military power abroad.
All of this, however, ignores the question of whether the United States has a moral responsibility to remain engaged in world affairs. From a practical or realistic perspective, the U.S. must remain heavily engaged. No other country possesses the U.S.'s combination of economic (which has declined in relative terms) and military power and shares the general U.S. view of foreign affairs. Threats to friendly and allied countries from larger stronger countries like Russia and China, and from nonstate actors like al Qaeda, require a continuous state of engagement.
Morally, the question of the U.S. role in world affairs is more complicated. The United States is a “superpower,” but it is not omnipotent. It is not possessed of infinite financial and material resources, and its population tires of protracted military engagements abroad – especially when those engagements lack a visible end state. Military threats to the U.S., its friends and allies, however, constitute the easy contingencies. Threats to peace and stability where no convincing U.S. national interest is present are the “rubber meets the road” scenarios that test the U.S. commitment to advance democracy, prevent tyranny, and aid those in danger. Consequently, decisions on whether to engage in humanitarian crises such as occurred in Rwanda in 1994, the Balkans during the 1990s, Haiti, and other crises have often been retroactively viewed as either hasty in engaging or morally delinquent in not engaging at all. Similarly, the U.S. commitment to aid Taiwan is one of the most dangerous potential flashpoints in the world, as the People’s Republic of China routinely threatens what it considers its renegade province with “reunification” by force. Whether the independence of democratic Taiwan is worth the loss of potentially thousands of American lives, however, is open to debate.
When widespread famine threatened the population of Somalia during the early 1990s, the United States lead an international coalition in intervening to ensure that warring factions did not deprive people of the aid that was flowing in. As some of those factions resisted U.S. efforts and interfered with the multinational mission, the U.S. employed military force. The resulting battle – the basis for the book Black Hawk Down – left deep scars on the American psyche that manifested themselves in the refusal to engage in preventing genocide in Rwanda. The divergent decisions and outcomes highlight the difficulty of articulating definitively what should be the U.S. role in world affairs. There is no question, however, that the United States has compelling national interests in remaining engaged, and a certain moral commitment to ensuring that genocidal policies such as occurred in Cambodia, Bosnia-Herzegovina, and Rwanda are not repeated.