In the mid-1960s, the United States Army already began looking beyond their ubiquitous M113 Armored Personnel Carrier (APC) series toward newer armored types designed for emerging battlefield threats. This led to the MICV-65 initiative which was eventually fulfilled by the M2 "Bradley" Infantry Fighting Vehicle (IFV) line (detailed elsewhere on this site) but one potential offshoot became the Armored Infantry Fighting Vehicle (AIFV), a further evolution of the M113A1 product, and went on to be used by many foreign forces.
With Army backing, FMC Corporation moved on a new version of the M113A1 which produced the "XM765" designator and two pilot vehicles followed for active testing. Key changes to the original design included the installation of firing ports for the passenger cabin as well as a wholly-enclosed, power-assisted turret mounting a more potent 25mm autocannon. These additions were to shore up inherent limitations observed in the M113 through practical service - drastically broadening inherent firepower and situational awareness for the occupants. The turret was an optional installation and could give way to a simpler gun ring mounting a 12.7mm heavy-caliber machine gun.
Army authorities were not impressed and pursued an altogether different offering which was adopted into service as the M2. However, the XM765 held enough potential that FMC continued developing the design for possible export sale. Some revisions later, the AIFV was born and the vehicle was presented to interested parties during the mid-1970s.
The Dutch though enough of the new tracked machine, and were turned off by the complexity and cost of the Bradley line, to offer a purchase contract for the AIFV that eventually totaled 2,079 units (several hundred of this total to be assembled locally by Dutch industry). In Dutch Army service, the vehicle carried the designation of "YPR-765" and a modernization program brought the group up to the "YPR-765A1" operating standard. First deliveries occurred in 1975.
Base Dutch models were the YPR-765 PRI ("Pantser Rups Infanterie") armed with a 25mm turreted autocannon and coaxial 7.62mm machine gun. Its base crew was three with seating for up to seven. The YPR-765 PRI.50 saw its turret removed and a gun ring added for mounting a 12.7mm heavy machine gun. Various other forms emerged from the YPR-765 PRCO ("Pantser Rups Commando") model including a company and battalion commander's vehicle, a mortar control vehicle and an artillery spotting vehicle. YPR-765 PRRDR carried a battlefield surveillance radar fit and YPR-765 PRGWT was an ambulance. YPR-765 PRMR fitted a 120mm mortar for mobile in-direct fire support and YPR-806 PRBG became a dedicated Armored Recovery Vehicle (ARV).
Dutch YPR-765s saw combat action in the War in Afghanistan before they were passed on to other operators. Frontline models were given up-armored kits to protect against guerilla RPG attacks and IEDs.
In 1979, the government of Belgium followed suit and took on a fleet of 514 AIFVs which would be produced locally. These began arriving in 1982 and were largely similar to the Dutch models. Service entry was in 1985 and the lot was eventually sold off to foreign parties. Belgian variants included the AIFV-B-C25 with 25mm turreted armament and smoke grenade launchers, the AIFV-B-MILAN Anti-Tank Guided Missile (ATGM) carrier, and the AIFV-B-.50 armed modestly with a sole 12.7mm heavy machine gun. Additionally the vehicle stowed a MILAN ATGM launcher unit as well as carried 2 x 71mm mortars. A training form was adopted as the AIFV-B-TRG. AIFV-B-CP served as a Command Post vehicle with suitable equipment fitted for the role (including local defense through a 12.7mm installation).
The Belgian Army succeeded its AIFV line with the MOWAG "Piranha" III 8x8 wheeled vehicles (detailed elsewhere on this site).
The Philippines contracted for 45 units all their own, the base model becoming the AIFV-25 armed with a 25mm autocannon and coaxial 7.62mm machine gun. AIFV-ARV was the Armored Recovery Vehicle (ARV) form.
The Turkish government added 1,698 AIFVs in 1989 with the lot partially built in Belgian factories and the rest completed locally. ACV-AAPC was used to designate the APC form and outfitted with a 12.7mm and a 7.62mm machine gun. Beyond its operating crew, the cabin could haul thirteen infantry under protection. ACV-AIFV marked a pair of 25mm cannon-armed models and ACV-ATV served in the anti-tank role, being outfitted with 2 x Hughes BGM-71 TOW missile launchers. The ACV-AMV was used as a mortar carrier, carrying an 81mm mortar system as well as a 7.62mm machine gun for local defense.
Further local work on the part of the Turks produced a continuing line of AIFV-related vehicles including the ACV-15/ACV-300 series by FNSS. Other additions included a Anti-Tank (AT) missile carrier, air defense variant, and up-armored form. A pair of offshoots offered different engine fits (300 or 350 horsepower). Regardless, all could trace their lineage back to the American AIFV. The last AIFV variant emerged from Turkish factories in 2004.
Second-hand operators went on to include Bahrain (ex-Dutch/Belgian models), Chile (ex-Dutch/Belgian), Egypt (ex-Dutch/Belgian), Jordan (ex-Dutch-Belgian), Lebanon (ex-Belgian), Malaysia, Morocco (ex-Belgian), and the UAE - these received from Turkey. Serbia operated a sole example captured from United Nations forces during the Yugoslav Wars of the 1990s.