Eighty-four F-86 Sabres of the 4th and 51st Fighter-Interceptor Groups were the first to arrive in the Sui-ho target area, tasked to provide cover against MiG attack and, according to one participant, to prevent MiGs from taking off by overflying their bases at low altitude, even though officially UN aircraft were not allowed to cross the Yalu except in hot pursuit. According to US sources, 160 MiGs took off before the arrival of the covering force but flew deeper into China, possibly fearing that their airfields were the targets, and none attempted to intercept the strike force.