In late 1961, the U.S. Army initiated studies for a possible replacement for the French SS.10 (MGM-21) and SS.11 (AGM-22) anti-tank missiles then in U.S. Army service. The studies called for a tube-launched, optically-tracked, and wire-guided missile (hence the acronym TOW), and design contracts were awarded to three companies. Hughes was eventually awarded the prime development contract for the BGM-71 missile, and from 1963 until 1968, TOW was developed in parallel for both ground- and air-launched applications. Missile rounds used in the development phase included the XMGM-71A (soon changed to XBGM-71A) prototype tactical round, the XBTM-71A unarmed training round, and the XBEM-71A, which was equipped with special telemetry electronics for test and evaluation purposes. In June 1968, the first full-scale production contract for the TOW was awarded to Hughes. In 1970, the BGM-71A missile (and the BTM-71A training round) was first fielded by operational U.S. Army ground troops, replacing the MGM-32 Entac missile and the M140 106 mm recoilless rifle. In 1972, the TOW was deployed for combat use in South-East Asia.