7.11 Interwar Foreign Policy

After World War I, the United States pursued a unilateral foreign policy that balanced isolationism with selective international engagement. As global threats grew in the 1930s, American policy shifted from strict neutrality toward support for democracies facing aggression, then full participation in World War II after Pearl Harbor.

What to Know About Interwar Foreign Policy

• The United States rejected the League of Nations and World Court but joined arms limitation efforts, including the Washington Naval Conference; the Kellogg-Briand Pact tried to outlaw war without a way to enforce it.
• The Dawes Plan used American loans to help Germany pay reparations, linking European war debts to the U.S. economy and later contributing to the global spread of the Great Depression.
• Under Roosevelt's Good Neighbor Policy, the United States pledged not to intervene in Latin American internal affairs, ended its right to intervene in Cuba, and emphasized trade and cultural exchange.
• The Great Depression and memories of World War I discouraged intervention, while the Neutrality Acts restricted arms sales and set "cash and carry" rules for trade with nations at war.
• After France fell in 1940, the United States increased support for Britain through the Destroyer-for-Bases Deal and Lend-Lease; the Atlantic Charter set out Roosevelt and Churchill's postwar principles.
• Japan's attack on Pearl Harbor on December 7, 1941, and Germany's and Italy's declarations of war brought the United States fully into World War II.

American Isolationism and Engagement

Following World War I, many Americans sought to limit foreign entanglements while still maintaining global influence. President Warren G. Harding promised a "return to normalcy" in foreign affairs, reflecting the nation's desire to focus on domestic prosperity rather than European problems.

The United States pursued a unilateral approach to international relations:

• Rejected membership in the League of Nations and the World Court
• Participated in arms limitation efforts while avoiding security alliances
• Used international investment and trade as primary tools of influence
• Used military intervention selectively, alongside investment and peace treaties, to advance its vision of how the world should be ordered
• Sought peace through negotiation rather than military commitments

The Washington Naval Conference (1921-1922) exemplified this approach by establishing tonnage ratios for major naval powers (US and UK: 5, Japan: 3, France and Italy: 1.75) to prevent costly arms races. Similarly, the Kellogg-Briand Pact (1928) represented America's idealistic attempt to outlaw war, though it lacked enforcement mechanisms.

Economic Diplomacy and Latin America

American foreign policy increasingly relied on economic tools to promote stability and advance national interests. Through the Dawes Plan (1924), American banks made loans to Germany, creating a circular flow where Germany paid reparations to Britain and France, which then repaid war debts to the U.S. This financial interconnection would later contribute to the global spread of the Great Depression.

In Latin America, the United States transformed its approach under the Good Neighbor Policy championed by President Roosevelt:

• FDR pledged at the 1933 Pan-American Conference never to intervene in Latin American internal affairs
• The U.S. terminated the Platt Amendment, ending the right to intervene in Cuba
• Emphasis shifted to reciprocal trade agreements and cultural exchanges
• This policy built hemispheric solidarity that would prove valuable during World War II

Response to Global Threats

As fascist and militarist regimes gained power in the 1930s, American policy gradually shifted from strict neutrality toward supporting democracies. The rise of Hitler in Germany, Mussolini in Italy, and Japanese militarism in Asia presented new challenges to international stability and American interests.

Most Americans remained opposed to direct intervention despite these growing threats. The Great Depression focused attention on domestic problems, while memories of World War I made many wary of foreign entanglements. President Roosevelt increasingly warned about totalitarian dangers while moving cautiously to avoid getting ahead of public opinion.

Neutrality Legislation and Path to War

Congress passed a series of Neutrality Acts designed to prevent American entanglement in foreign wars:

• The 1935 Act prohibited arms sales to nations at war
• The 1937 Act created "cash and carry" provisions for trade with belligerents
• These laws initially limited America's ability to support democracies against aggressors

As World War II began in Europe, Roosevelt sought greater flexibility to help Britain and France. After the fall of France in 1940, American support for Britain accelerated through the Destroyer-for-Bases Deal, the Selective Service Act (establishing the first peacetime draft), and the Lend-Lease Act of 1941, which allowed Britain, and later the Soviet Union and China, to receive American equipment.

In August 1941, Roosevelt and Churchill issued the Atlantic Charter outlining principles for a postwar world based on democracy and self-determination. Though not yet at war, the United States had clearly aligned itself with Britain against Nazi Germany.

Rising tensions with Japan culminated in the December 7, 1941 attack on Pearl Harbor, killing over 2,400 Americans. Germany and Italy declared war on the United States days later, bringing America fully into the global conflict and ending the interwar period of American foreign policy.

The interwar years witnessed America's gradual evolution from post-WWI isolationism to world leadership. Throughout this period, American policymakers balanced traditional desires to avoid entanglements with the growing reality that events abroad threatened national security and democratic values.