Overview

Since 1915, the United States has evolved from a cautious world participant to a dominant global power. American diplomacy has been shaped by world wars, ideological rivalry, trade agreements, and security challenges. The country’s engagement with the world reflects changing goals, values, and threats over time.

Key Themes and Events

• World War I: The U.S. joined the war in 1917 to “make the world safe for democracy.” President Wilson’s Fourteen Points emphasized self-determination and the League of Nations, but the Senate rejected U.S. participation in the League.
• World War II and Global Leadership: After Pearl Harbor (1941), the U.S. mobilized for total war. Victory led to a leadership role in creating the United Nations and shaping postwar Europe through the Marshall Plan.
• The Cold War: The U.S. and Soviet Union competed for influence globally. Key events include the Truman Doctrine, NATO, Korean and Vietnam Wars, Cuban Missile Crisis, and the fall of the Berlin Wall (1989).
• Trade and Globalization: The U.S. promoted international trade through agreements like NAFTA and participation in organizations like the WTO. The economy became deeply interconnected with global markets.
• Post–9/11 Foreign Policy: Terrorist attacks on September 11, 2001, led to wars in Afghanistan and Iraq. The U.S. increased homeland security efforts and expanded its counterterrorism strategy.
• Contemporary Diplomacy: Recent decades include climate agreements, nuclear negotiations, and shifting alliances. Debates continue over interventionism, isolationism, and global leadership roles.

Quick Tip

Understand how U.S. diplomacy changed after both World Wars and during the Cold War. CLEP may test on major treaties, military conflicts, and shifts from isolationism to global engagement.