The Korean War began in June 1950 when North Korean troops invaded South Korea in an attempt to spread communism throughout the Korean peninsula. The United Nations authorized a force led by General Douglas MacArthur to defend South Korea. Fighting between UN and Chinese-backed North Korean forces resulted in back-and-forth gains until an armistice established the border between North and South Korea along the original 38th parallel division. The Korean War highlighted tensions between the US and USSR in containing the spread of communism during the Cold War.