By 1992, the Russian Ministry of Defence announced that it could no longer afford to manufacture two main battle tanks in parallel. Since both the "quality" T-80U and the cheaper "quantity" T-72B were being built at different plants, and each plant was critical to the economy of its city, the government gave small orders to both. Omsk built five T-80Us and Nizhny Tagil built fifteen T-72s, and both built more in the hopes of winning large export orders. Nizhny Tagil had built a few T-72BAs, T-72Bs upgraded with a third generation add-on explosive reactive armour (ERA) called Kontakt-5, which was already in service on the T-80U.
To further improve the T-72's export prospects and its chances of being selected as Russia's sole production main battle tank, the T-80U's more sophisticated fire control system was also added to produce a vehicle designated T-72BU. The T-90 was developed by the Kartsev-Venediktov Design Bureau at the Uralvagonzavod factory in Nizhny Tagil. The production model is based on the T-72BM, with some added features from the T-80 series.
The T-90 with an 830 hp (620 kW) engine went into low-level production in 1993, based on a prototype designated T-88. It features a new generation of Kontakt-5 explosive reactive armour on its hull and turret. Of conventional layout, the T-90 represents a major upgrade to every system in the T-72, including the main gun. The T-90S have been identified as export model. The references to a T-90E appear to be unsubstantiated. The T-90 is fitted with a "three-tiered" protection system: the first tier is the composite armour in the turret, second tier is third generation Kontakt-5 ERA and third tier is a Shtora-1 countermeasures suite.
T-90s were used in combat for the first time during the invasion of Dagestan in 1999.
The T-90's main armament is the 2A46M 125 mm smoothbore tank gun. This is a highly modified version of the Sprut anti-tank gun, and is the same gun used as the main armament on the T-80-series tanks. It can be replaced without dismantling the inner turret and is capable of firing armour-piercing fin-stabilised discarding sabot (APFSDS), high-explosive anti-tank (HEAT-FS), and high explosive fragmentation (HE-FRAG) ammunition, as well as 9M119M Refleks anti-tank guided missiles. The Refleks missile has semi-automatic laser beam-riding guidance and a tandem hollow-charge HEAT warhead. It has an effective range of 100 m to 6 km, and takes 17.5 seconds to reach maximum range. Refleks can penetrate about 950 millimetres (37 in) of steel armour and can also engage low-flying air targets such as helicopters.
The NSV 12.7mm (12.7x108) remotely controlled anti-aircraft Heavy machine gun can be operated from within the tank by the commander and has a range of 2 km and a cyclic rate of fire of 700–800 rounds per minute with 300 rounds available (the NSV was replaced by the Kord heavy machine gun in the late 1990s). The PKMT 7.62mm (7.62x54mm R) coaxial machine gun weighs about 10.5 kg while the ammunition box carries 250 rounds (7,000 rounds carried) and weighs an additional 9.5 kg.
Like other modern Russian tanks the 2A46M in the T-90 is fed by an automatic loader which removes the need for a manual loader in the tank and reduces the crew to 3 (commander, gunner, and driver). The autoloader can carry 22 ready-to-fire rounds in its carousel and can load a round in 5–8 seconds. It has been suggested that the automatic loaders on modern T-90 tanks have been modified to take advantage of newer ammunition such as the 3BM-44M APFSDS, which like the US M829A3 penetrates armour better than the previous shorter rounds. HEAT rounds that can be fired from the 2A46M includes the 3BK21B (with a Depleted uranium liner), 3BK29 (with a credited penetration of 800 mm RHA equivalency), and the 3BK29M (with a Triple-tandem charge warhead). Additionally the T-90 features the Ainet fuse setting system which allows the tank to detonate 3OF26 HE-FRAG rounds at a specific distance from the tank as determined by the gunners laser rangefinder, improving its performance against helicopters and infantry. Accurate firing range HE-Frag-FS 10 km, APFSDS 4 km
Fire-control system T-90 showed the following features combat shooting during state testing. Heavily armoured targets at ranges of up to 5 km tank T -90 strikes on the move (up to 30 km/h) with a high probability hit the first shot. During state testing was made 24 launch missiles at ranges of 4–5 km and they all hit the target (all missile launches were made by inexperienced professionals), an experienced gunner for 54 traffic at speeds of 25 km/h, 7 real shells hit armoured targets located at ranges of 1,500–2,500.
Fire-control system on the T-90 includes the PNK-4S/SR AGAT day and night sighting system mounted at the commanders station which allows for night time detection of a tank sized target at ranges between 700 and 1100 metres depending on the version of the sight. Early models of the T-90 were equipped with the TO1-KO1 BURAN sight but later models (T-90S) were upgraded to use the ESSA thermal imaging sight, which allows for accurate firing to a range of 5,000–8,000 m using the CATHERINE-FC thermal camera produced by Thales Optronique. The gunner is also provided with the 1G46 day sighting system which includes a laser range finder, missile guidance channel and allows tank-sized targets to be detected and engaged at 5 to 8 kilometres (3.1 to 5.0 mi). The driver uses a TVN-5 day and night sight. In 2010, Russia started licensed production of Thales-developed Catherine FC thermal imaging cameras for T-90M tanks, a Russian daily said. These thermal imagers are also present on T-90M "Bhishma" built in India under licence.