The Korean War began in 1950 when North Korea invaded South Korea, leading to fighting between North Korean and Chinese forces and United Nations forces led by the United States. After intense negotiations, an armistice was signed in 1953 that split Korea along the original border at the 38th parallel and ended direct fighting, though a peace treaty was never signed and the two Koreas remain divided. The war caused massive casualties, with over 1 million North and South Korean deaths as well as 55,000 American deaths. While the US prevented South Korea from falling, it failed to reunify the Korean peninsula.