From Wikipedia

 Korean War In Colour

 The United Nations, particularly the United States, came to the aid of South Korea in repelling the invasion. A rapid UN counter-offensive drove the North Koreans past the 38th Parallel and almost to the Yalu River, causing the People's Republic of China (PRC) to enter the war on the side of the North. The Chinese launched a counter-offensive that repelled the United Nations forces past the 38th Parallel. The Soviet Union materially aided both the North Korean and Chinese armies. In 1953, the war ceased with an armistice that restored the border between the Koreas near the 38th Parallel and created the Korean Demilitarized Zone (DMZ), a 2.5-mile (4.0 km) wide buffer zone between the two Koreas. Minor outbreaks of fighting continue to the present day.