Winston Churchill gave a famous speech on May 13, 1940 outlining Britain's policy of total victory against Nazi Germany "at all costs". After Germany's swift defeat of France, Britain stood alone against Hitler. The Battle of Britain in 1940 was Hitler's first major defeat as the Royal Air Force prevented Germany from gaining air superiority needed to invade. The US took steps to support Britain through destroyers-for-bases deal and passing the Lend-Lease Act in 1941 to provide military aid. Japan's expansionism threatened US and British interests in the Pacific, leading to increased tensions and an eventual Japanese attack on Pearl Harbor on December 7, 1941 that drew the US into World War II.