After the costly U.S. involvement in World War I, isolationism grew within the nation. Congress refused membership in the League of Nations, and in response to the growing turmoil in Europe and Asia, the gradually more restrictive Neutrality Acts were passed, which were intended to prevent the U.S. from supporting either side in a war. President Franklin D. Roosevelt sought to support Britain, however, and in 1940 signed the Lend-Lease Act, which permitted an expansion of the "cash and carry" arms trade to develop with Britain, which controlled the Atlantic sea lanes.