In early 1963, the M72 LAW was adopted by the U.S. Army and U.S. Marine Corps as their primary individual infantry anti-tank weapon, replacing the M31 HEAT rifle grenade and the M20A1 "Super Bazooka" in the U.S. Army. It was subsequently adopted by the U.S. Air Force to serve in an anti-emplacement/anti-armor role in Air Base Defense duties. It had been intended in the early 1980s that the M72 would be replaced by the FGR-17 Viper. However, this program was canceled by Congress and the M136 AT4 was introduced instead.