The Korean War was primarily the result of an agreement of the victorious Allies at the end of World War II. The Korean Peninsula had been ruled by the Empire of Japan from 1910, and following it’s surrender in 1945 the peninsula was divided the along the 38th parallel, with USA forces occupying the southern half and Soviet military forces occupying the northern half.
The North established a communist government, while the South established a right-wing government and the 38th parallel increasingly became a political border between the two Korean states. Tension in the area intensified as cross-border skirmishes and raids persisted until North Korean forces invaded South Korea in 1950.
The USA and other countries passed a Security Council resolution in the United Nations authorizing military intervention in Korea, which was able to be passed because the Soviet Union was boycotting the council at the time.
The USA provided most of the soldiers which aided South Korean forces, with mixed results until the People’s Republic of China, keen to assert itself on the world stage, entered the war on the side of North Korea forcing the Southern-allied forces to retreat behind the 38th Parallel. The Soviet Union had no boots on the ground, but provided material aid to both the North Korean and Chinese armies.
The fighting ended in 1953 when the armistice agreement was signed by all involved, apart from the South Koreans, which means the two countries are still technically at war today. However the agreement restored the border between the nations near the 38th Parallel and created the Korean Demilitarized Zone (DMZ). None of the countries involved are entirely fond of the others some sixty years later.
The DMZ is a 4km wide fortified buffer zone between the two Korean countries, which is a powder keg that always seems ready to go off, so it sounds like just the sort of place you should go to on holiday! I’ll send you a postcard.