In the 1980s, the United States Army began looking for an air-portable replacement for their M551 Sheridan light tanks. Several attempts over the years to update or replace the Sheridan had proved unsuccessful. The Armored Gun System competition was initiated and in 1992 FMC/United Defense's vehicle was selected. In addition to being expected to replace the Sheridan in the 82nd Airborne Division, it was also expected to replace TOW anti-tank missile-equipped Humvees in the 2nd Armored Cavalry Regiment. A December 1993 Department of Defense Inspector General report criticized the program for producing an overweight tank that did not meet the Army's requirements for air mobility, and recommended delaying low-rate initial production of the tank until the airdrop requirement could be met. Six prototypes were eventually built for the US Army under the designation XM8 AGS. The first of these arrived at Fort Knox in April 1995. The M8 was later type-classified by the US Army in late 1995 and initially slated for production in 1996. The M8 project was canceled in 1997 to free up money for other fledgling programs. Between 1999 and 2000 the M8 AGS was again evaluated by the US Army for upcoming medium brigade combat teams planned by General Eric Shinseki, in which the Stryker was eventually selected. In March 2004 at the 82nd Airborne Division's request, the Army approved the transfer of four production vehicles from United Defense's facility in York, Pennsylvania to the 82nd at Fort Bragg in North Carolina. However, as of June 2004, this transfer was on hold pending an "ongoing analysis." United Defense had reportedly sought overseas customers, without success. In late 1997 they parted with FNSS Defence Systems to offer the M8 AGS to the Turkish Land Forces Command. As of 2006, Taiwan at one point expressed interest as a replacement for its fleet of M24 Chaffee/M41 Walker Bulldog light tanks but would not commit following cancellation by the US. BAE Systems was awarded a contract, along with General Dynamics, by the US Army as part of the Mobile Protected Firepower program on 17 December 2018 to create an air transportable light tank to assist infantry brigades in forced entry operations; BAE submitted an updated M8 design with new capabilities and components. Requirements called for a tracked vehicle armed with a 105 mm or 120 mm cannon, which would not need to be air-droppable, but two would fit in a C-17 Globemaster and land on an airfield secured by infantry. The two companies will build 12 prototypes each and begin delivering them in 14 months to begin testing in spring 2020, down-select to a winner by 2022, and begin fielding the first of 504 vehicles by 2025.
Design
The basic hull of the M8 is made of welded aluminum alloy, with a modular armoring system that allows the vehicle to be equipped according to requirements. The Level I armor package is designed for the rapid deployment role and can be airdropped from a C-130 Hercules and protects the vehicle against small-arms fire and shell splinters. The Level II armor package can still be carried by C-130, but must be airlanded and is designed for use by light forces in a more serious threat environment, while level III armor is designed for contingency operations and is supposed to provide protection against light handheld anti-tank weapons. Level III armor cannot be carried by C-130. All versions are air-transportable by C-5 Galaxy and C-17 Globemaster III. The M8 is armed with the M35 rifled autoloading 105 mm cannon main gun with an M240 7.62 mm machine-gun mounted coaxially. The M35 has a rate of fire of approximately 12 rounds per minute, with a ready capacity of 21 rounds and 24 more in hull stowage. A Browning M2.50 caliber heavy machine gun is mounted in a manually-operated pintle on the commander's hatch. Power is provided by a Detroit Diesel 6V-92TIA diesel developing 550 hp.
Variants
M8 Thunderbolt / AGS 120 A single technology demonstrator built by United Defense and demonstrated in 2003, incorporating a 120mm smoothbore cannon fitted with an autoloader. Line of Sight Anti-Tank In 1994 Loral Vought Systems was awarded a contract to integrate LOSAT on to an M8 AGS hull. M8 MPF is a light tank for US Army offered in Mobile Protected Firepower program.
