Canada's strong attachment to the British Empire and Commonwealth led to major participation in British military efforts in the Second Boer War, World War I and World War II. Since then, Canada has been an advocate for multilateralism, making efforts to resolve global issues in collaboration with other nations. During the Cold War, Canada was a major contributor to UN forces in the Korean War and founded the North American Aerospace Defense Command (NORAD) in cooperation with the United States to defend against potential aerial attacks from the Soviet Union.