On 25 June 1950, North Korean forces invaded South Korea. Led by the U.S., a 16-member coalition undertook the first collective action under the United Nations Command (UNC) in defense of South Korea. Oscillating battle lines inflicted a high number of civilian casualties and wrought immense destruction. With the People's Republic of China's entry on behalf of North Korea in late 1950, the fighting came to a stalemate close to the original line of demarcation. Armistice negotiations, initiated in July 1951, finally concluded on 27 July 1953 at Panmunjeom, now in the Demilitarized Zone (DMZ). Following the armistice, the South Korean government returned to Seoul on the symbolic date of 15 August 1953.