Critical Foreign Policy Decisions

Why This Matters

Understanding America's critical foreign policy decisions isn't just about memorizing dates and doctrines—it's about recognizing the patterns of thinking that drove U.S. leaders to act on the world stage. You're being tested on how American foreign policy evolved from hemispheric defense to global intervention, and why policymakers chose engagement over isolation (or vice versa) at key turning points. These decisions reveal fundamental tensions in American identity: Should the U.S. lead the world or focus on domestic affairs? Is spreading democracy a moral obligation or imperial overreach?

The AP exam loves to ask about continuity and change in foreign policy, so you need to understand how later policies built on earlier foundations—the Roosevelt Corollary extending the Monroe Doctrine, or the Truman Doctrine applying containment principles established after WWII. Pay attention to causes, effects, and debates surrounding each decision. Don't just memorize that the Marshall Plan happened in 1948—know that it represented economic containment and sparked debates about the proper scope of American power abroad.

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Establishing Hemispheric Dominance

The United States first asserted itself internationally by claiming special authority over the Western Hemisphere. These policies established the precedent that American security interests extended beyond U.S. borders—a foundation for all future interventionism.

Monroe Doctrine (1823)

• Declared the Western Hemisphere closed to European colonization—President Monroe's message to Congress warned that any European intervention would be considered a hostile act against the U.S.
• Reflected post-War of 1812 nationalism and the desire to protect newly independent Latin American republics from reconquest
• Established a foundational principle that later presidents would expand and reinterpret to justify intervention throughout the Americas

Roosevelt Corollary (1904)

• Transformed the Monroe Doctrine from defensive to interventionist—Theodore Roosevelt claimed the U.S. had the right to exercise "international police power" in Latin America
• Justified repeated U.S. military interventions in the Caribbean and Central America, including occupations of Cuba, Haiti, Nicaragua, and the Dominican Republic
• Represented Progressive-era confidence in American exceptionalism and the belief that the U.S. could "civilize" unstable nations

Acquisition of the Panama Canal (1903)

• Secured strategic control of a vital trade route—the canal cut shipping time between the Atlantic and Pacific by thousands of miles, transforming global commerce
• Demonstrated willingness to manipulate Latin American politics—the U.S. supported Panama's revolution against Colombia to gain canal rights
• Enhanced U.S. naval power projection and cemented American dominance in the Caribbean, making the "American lake" concept a reality

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Emergence as a World Power

The late 19th and early 20th centuries saw the U.S. abandon its continental focus and compete with European empires for global influence. These decisions marked America's transformation from regional power to imperial nation.

Spanish-American War (1898)

• Launched the U.S. as an imperial power—victory over Spain brought control of Puerto Rico, Guam, and the Philippines, giving America overseas colonies for the first time
• Sparked intense domestic debate over imperialism, with anti-imperialists arguing that colonizing other peoples contradicted American democratic values
• Demonstrated the influence of yellow journalism and public opinion in driving foreign policy decisions—"Remember the Maine" became a rallying cry

Open Door Policy in China (1899)

• Advocated equal trading rights for all nations in China, preventing European powers from carving the country into exclusive spheres of influence
• Protected American commercial interests without requiring territorial conquest—a distinctly American approach to imperialism
• Committed the U.S. to Asian affairs, setting the stage for future conflicts over influence in the Pacific region

Wilson's Fourteen Points (1918)

• Proposed a new framework for international relations based on self-determination, free trade, and collective security through a League of Nations
• Represented idealistic internationalism—Wilson believed American democratic principles should reshape the world order after WWI
• Failed domestically when the Senate rejected the League, revealing tensions between executive foreign policy ambitions and Congressional authority

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The Isolationism-Intervention Debate

Between the world wars, Americans fiercely debated whether global engagement served national interests. This period reveals how domestic politics and public opinion constrain foreign policy choices.

Isolationism in the 1920s and 1930s

• Reflected public disillusionment with WWI—many Americans believed U.S. entry had been a mistake driven by bankers and arms manufacturers
• Produced the Neutrality Acts (1935-1937), which prohibited arms sales and loans to belligerent nations, attempting to prevent the entanglements that had drawn the U.S. into WWI
• Created tension between isolationist sentiment and FDR's recognition that fascist aggression threatened American security

Lend-Lease Act (1941)

• Circumvented neutrality restrictions by allowing the U.S. to "lend" military equipment to Allied nations—FDR compared it to lending a neighbor a garden hose to fight a fire
• Marked the effective end of isolationism and committed American industrial capacity to Allied victory months before Pearl Harbor
• Demonstrated executive creativity in foreign policy—FDR found ways to support Britain despite Congressional restrictions and public reluctance

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Cold War Containment

After WWII, the United States committed to preventing Soviet expansion worldwide. Containment became the organizing principle of American foreign policy for four decades, justifying military alliances, economic aid, and armed intervention.

Truman Doctrine (1947)

• Committed the U.S. to supporting "free peoples" resisting communism—initially applied to Greece and Turkey, where communist insurgencies threatened pro-Western governments
• Established containment as official policy, framing the Cold War as an ideological struggle between freedom and totalitarianism
• Expanded presidential power in foreign affairs and set precedents for U.S. intervention in countries facing communist threats

Marshall Plan (1948)

• **Provided $13 billion in economic aid** to rebuild Western European economies devastated by WWII—equivalent to over$150 billion today
• Combined humanitarian goals with strategic interests—prosperous democracies were less likely to turn communist
• Strengthened transatlantic ties and demonstrated that containment could work through economic means, not just military force

NATO Formation (1949)

• Created the first peacetime military alliance in American history, committing the U.S. to defend Western Europe against Soviet attack
• Represented a permanent break from isolationism—American troops would remain stationed in Europe indefinitely
• Established collective security through Article 5, which declared an attack on one member an attack on all

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Containment in Action: Hot Wars of the Cold War

Containment theory led to direct military intervention when communist forces threatened to expand. These conflicts tested the limits of American power and public support for interventionist foreign policy.

Korean War (1950-1953)

• First major military test of containment—when North Korea invaded South Korea, Truman committed U.S. forces under UN authorization without a formal declaration of war
• Ended in stalemate at the 38th parallel, demonstrating the limits of "rollback" and establishing the pattern of limited Cold War conflicts
• Set precedent for presidential war-making without Congressional declaration, expanding executive power in foreign affairs

Cuban Missile Crisis (1962)

• Brought the world closest to nuclear war—Kennedy's naval blockade of Cuba forced Khrushchev to remove Soviet missiles after 13 days of intense brinkmanship
• Demonstrated the dangers of nuclear deterrence and led both superpowers to seek arms control agreements
• Resulted in the "hotline" agreement and showed that direct communication could prevent miscalculation during crises

Vietnam War (1955-1975)

• Applied containment to Southeast Asia based on the "domino theory"—if Vietnam fell to communism, neighboring countries would follow
• Escalated dramatically under Johnson following the Gulf of Tonkin Resolution (1964), which gave the president broad war-making authority
• Sparked massive domestic opposition and ended in defeat, leading to the "Vietnam Syndrome"—public reluctance to support military interventions abroad

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Quick Reference Table

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Self-Check Questions

1. Which two policies represent the evolution of U.S. claims to authority in the Western Hemisphere, and how did the second expand upon the first?

2. Compare the Spanish-American War and the Open Door Policy as approaches to American expansion—what did each seek, and how did their methods differ?

3. How did the Lend-Lease Act represent a departure from the foreign policy principles embodied in the Neutrality Acts? What changed American thinking?

4. If an FRQ asked you to explain how the U.S. implemented containment through both military and economic means, which policies would you use as evidence?

5. Compare and contrast the Korean War and Vietnam War in terms of their outcomes and effects on American public opinion—why did one maintain support while the other generated massive opposition?