The two countries that fought in the Korean War from 1950 to 1953 were North Korea and South Korea. The war began when North Korea, backed by China and the Soviet Union, invaded South Korea on June 25, 1950. The conflict escalated into a proxy war involving the United States, which supported South Korea, and resulted in heavy casualties and widespread destruction. The war ended with an armistice agreement on July 27, 1953, but no formal peace treaty was signed, leaving the Korean Peninsula divided to this day along the demilitarized zone (DMZ).