Shortly after the attack of Pearl Harbor, and the American entry into the war, Japanese troops invaded the Aleutian Islands. RCAF planes flew anti-submarine patrols against the Japanese while on land, Canadian troops were deployed side by side with American troops against the Japanese. Owing to circumstances, Canadians troops were only once sent into combat during the Aleutian campaign during the invasion of the island of Kiska. However, the Japanese had already withdrawn their forces at that point.