The Tangos, also known as Armoured Troop Carriers (ATC), were LCM-6 landing crafts modified for riverine patrol missions. They were used by the Mobile Riverine Force of the United States Army in the Vietnam War. The troops of the 9th Infantry Division used them more than other groups in the earlier parts of the war, but as they proved themselves they were deployed elsewhere. They were also used by South Vietnamese and Cambodian troops.
Many were equipped with helicopter decks. They could be told from the LCM-6 by their distinctive bow ramp. They also had an armoured superstructure to protect from rockets. The ATC, the most common variant, carried four M1919 Browning machine guns, two Mk 16 20 mm cannons, and one Mk 19 grenade launcher. Some carried flamethrowers. These were known as "Zippos". The "Monitor" was another version, which was used as a floating tank. In addition to the ATC’s armament, it also carried an 81 mm mortar and a 105 mm howitzer. There was also a command and communications boat, known as the "Charlie". Many tangos were also converted into refueling boats.
The ATC weighed 66 tons, and 56.5-foot (17.2 m) long. They had a crew of 7. They had a top speed of 8.5 knots (15.7 km/h; 9.8 mph).
The Tango saw combat with the 113th Task Force of the Mobile Riverine Force in Operation Game Warden.