jul 27, 1953 - End of Korean War
The fighting ended on 27 July 1953, when an armistice was signed. The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners. However, no peace treaty has been signed, and according to some sources the two Koreas are technically still at war, engaged in a frozen conflict.
Added to timeline:
20th century US foreign policy