LOSAT (Line-of-Sight Anti-Tank) is a U.S. surface-to-surface missile system designed by Lockheed Martin to defeat tanks and other individual targets. Instead of using a High Explosive Anti-Tank warhead like other anti-tank missiles, the LOSAT employs a solid Tungsten Kinetic energy penetrator to punch through armor, much like the APFSDS (Armour Piercing Fin Stabilized Discarding Sabot) rounds used by U.S. tanks. The LOSAT weapon system is very light; it is designed to be mounted onto a Humvee while allowing the vehicle to remain air-portable. With a speed of 5,000 ft/s (5,500 km/h or 1,520 m/s), the LOSAT is the world’s fastest missile.

The LOSAT program was terminated in the summer of 2004, before full rate production commenced.

Losat (Line-of-Sight Anti-Tank) humvee