Work began on an anti-radar missile derived from the Kh-66 in 1972, using a passive radar seeker and SUR-73 autopilot. The long-range Kh-31 anti-radar missile came out of the same project. The Kh-27 began state testing on a MiG-27 on 8 August 1975but did not enter service until 2 September 1980. It was assigned the NATO reporting name AS-12 'Kegler' and in effect it replaced the much heavier Kh-28 (AS-9 'Kyle').
In 1973 Victor Bugaiskii was appointed head engineer of the bureau and he started work on combining the Kh-23M, Kh-25 and Kh-27 into a single modular system to reduce costs and improve tactical flexibility. The Kh-27 missile was chosen as a basis, due to its more powerful rocket engine and new autopilot. This was completed by the end of 1978, resulting in the Kh-25MP (anti-radar), Kh-25ML (laser-guided) and Kh-25MR (radio-guided) family. NATO continued to refer to these as the AS-12 and AS-10 respectively, even though they could now be switched by a simple change of seeker head.