MGM-166 LOSAT / KEM

The MGM-166 LOSAT, or Line-of-Sight Anti-Tank, was a U.S. program associated with Lockheed Martin and earlier Vought/Loral work. It attempted to defeat armored targets with a high-speed kinetic penetrator rather than a conventional explosive anti-tank warhead. The concept promised very short time of flight and high lethality, but it remained a specialized development path.

LOSAT used a large missile launched from a vehicle-mounted system and guided along line of sight toward armored targets. Its kill mechanism depended on impact energy from a solid penetrator, making it conceptually closer to tank-gun kinetic rounds than to normal anti-tank guided missiles. That also made missile size, launch signature, and platform integration major challenges.

The LOSAT program reached testing and low-rate production activity, but broad procurement was curtailed as the Army shifted toward follow-on Compact Kinetic Energy Missile ideas. Its significance is therefore technological rather than operational. It shows how anti-armor designers explored alternatives to shaped-charge missiles as active protection and heavy armor evolved.