The Korean War began in June 1950 when troops from North Korea invaded South Korea in an attempt to reunify the Korean peninsula under Communist rule. The United States led United Nations forces to defend South Korea from the invasion. After initial success pushing the North Koreans back, China entered the war to support North Korea, and fighting became stalemated near the original border. An armistice in 1953 established a demilitarized zone at the 38th parallel, dividing the Korean peninsula much as it had been after World War II.