"The Korean War was fought between North Korea and South Korea; it began on 25 June 1950 when North Korea invaded South Korea and ceased after an armistice on 27 July 1953. North Korea was supported by the People's Republic of China and the Soviet Union while South Korea was supported by the United Nations Command (UNC) led by the US."
Fine. Don't take my word for it. Go look.
From https://en.wikipedia.org/wiki/Korean_War:
"The Korean War was fought between North Korea and South Korea; it began on 25 June 1950 when North Korea invaded South Korea and ceased after an armistice on 27 July 1953. North Korea was supported by the People's Republic of China and the Soviet Union while South Korea was supported by the United Nations Command (UNC) led by the US."