The UN September 1950 counteroffensive was a large-scale offensive by United Nations Command (UN) forces against North Korean forces commencing on 23 September 1950. Following the UN counterattack at Inchon on 15 September, on 16 September UN forces within the Pusan Perimeter broke out of the perimeter, driving back the North Koreans and moved north linking up with the UN forces coming from Inchon near Osan on 27 September.