GLCM was developed as a ground-launched variant of the Tomahawk missile in use by the U.S. Navy (along with an undeveloped air-launched version, the Medium Range Air to Surface Missile (MRASM)) Unlike other variants of the Tomahawk, the GLCM carried only a W84 thermonuclear warhead; no conventional capability was provided. The W84 warhead is a 0.2–150kt variable-yield weapon. This yield contrasts with the yield of the W80 warhead found on other versions of the Tomahawk and on the ALCM from which the W84 was derived, which has a selectable yield of 5 or 150 kt. The Pentagon credited the GLCM with a range of 2000–2500 kilometers. Like other U.S. cruise missiles of this period, accuracy after more than 2000 km of flight was approximately 30 meters. The missile was entirely subsonic, powered by a turbofan engine with a rocket booster assisting at launch.