The AGM-129 ACM (Advanced Cruise Missile) was a low-observable, subsonic, turbofan-powered, air-launched cruise missile originally designed and built by General Dynamics and eventually acquired by Raytheon Missile Systems. Prior to its withdrawal from service in 2012, the AGM-129A was carried exclusively by the US Air Force's B-52H Stratofortress bombers.

In 1982, the US Air Force began studies for a new cruise missile with low-observable characteristics after it became clear that the AGM-86B cruise missile would have difficulty penetrating future air defense systems. The AGM-86B relied on low-altitude flight to penetrate the Soviet air defense system centered on surface to air missiles. The deployment of the airborne early warning systems, together with the Zaslon PESA radar on MiG-31 and Myech radar on Su-27 interceptors, all three "look-down/shoot-down" radars, reduced the likelihood that the low-altitude AGM-86B would reach its target.

The solution was to incorporate various "low-observable" ('stealth') technologies into a new Advanced Cruise Missile system.

In 1983, General Dynamics Convair Division (GD/C) was awarded a development contract for the AGM-129A (the losing design was Lockheed Corporation's Senior Prom). The AGM-129A incorporated body shaping to reduce the missile's radar cross section. The engine air intake was flush mounted on the bottom of the missile to further improve radar cross section. The jet engine exhaust was shielded by the tail and cooled by a diffuser to reduce the infrared signature of the missile. To reduce electronic emissions from the missile, the radar used in the AGM-86B was replaced with a combination of inertial navigation and terrain contour matching (TERCOM) enhanced with highly accurate speed updates provided by a Lidar Doppler velocimeter.

These changes made the AGM-129A more difficult to detect and allowed the missile to be flown at higher altitude. The newer Williams International F112-WR-100 turbofan engine increased range by about 50%. The newer guidance system increased accuracy to a quoted figure of between 30 m (100 ft) and 90 m (300 ft).

The AGM-129A, like the AGM-86B, is armed with a W80-1 variable-yield nuclear warhead.

The first test missile flew in July 1985, and the first production missiles were delivered to the US Air Force in 1987. The development program experienced some hardware 'quality control' problems and testing mishaps. The flight test program took place during a period of high tension between the machinists' union and GDC management, with a 3+1⁄2-week-long strike occurring in 1987. US Congressman Les Aspin called the ACM a procurement disaster with the worst problems of any of the eight strategic weapons programs his committee had reviewed. The US Congress zeroed out funding for the ACM program in 1989. Manufacturing 'quality' problems led the US Air Force to stop missile deliveries in 1989 and 1991. McDonnell Douglas was invited to qualify as a second source for missile production. In early 1989, the United States requested and received permission to test the AGM-129A in Canada.

Plans called for producing enough missiles to replace the approximately 1,461 AGM-86B's at a rate of 200 missiles per year after full-rate production was achieved in 1993. In January 1992, the end of the Cold War led US President George H. W. Bush to announce a major cutback in total ACM procurement. The President determined that only 640 missiles were needed. The ACM program was later reduced still further to 460 missiles. In August 1992, General Dynamics sold its missile business to Hughes Aircraft Corporation. Five years later in 1997, Hughes Aircraft Corporation sold its aerospace and defense business to the final production contractor Raytheon.