Its high-performance opposed-piston engine makes it a fast tank, comparable to other modern MBTs with a power-to-weight ratio of about 26 horsepower per tonne (19 kW/t).

The T-84-120 Yatagan is a prototype model intended for export, mounting a 120 mm gun able to fire NATO-standard tank ammunition and anti-tank guided missiles.

The disadvantages of the gas-turbine engine were readily apparent, and so several design projects were initiated to adopt a diesel alternative.

Leningrad Kirov Plant (LKZ) began work in 1975 with a diesel 2V16 1500 hp engine on a T-80B chassis.

Further work on these was not continued, as the main focus at the time was on the gas-turbine engine favored by Defence Minister Dmitry Ustinov.

[3] In 1975, Kharkiv Morozov Machine Building Design Bureau (KMDB) began work on the Object (Ob.)

[3] After the death of Ustinov in 1984, the strength of the design bureau of the LKZ began to weaken and the Ministry of Defense started to think seriously about equipping the T-80 tanks with diesel engines.

The Soviet Army noted problems with the tank, and full-scale production was delayed to make changes.

It was first publicly shown at the 1990 Moscow Victory Day Parade, then later in the 1991 Soviet coup d'état attempt.

[6] The tank featured a 120mm smooth bore gun that was capable of firing AT-11 Sniper ATGMs, a reloading mechanism and blow-out panels.

It is also designed to perform well in hot climates, and includes an air-conditioned crew compartment (operating temperature range is claimed to be −40 to 55 °C).

The ammunition includes high explosive fragmentation (HE-FRAG), armour-piercing fin-stabilized discarding sabot (APFSDS) kinetic energy penetrator, and high-explosive anti-tank (HEAT).

The main gun can also fire a laser-guided missile against armoured ground vehicles and hovering helicopters within the range of 5,000m.

The advanced fire-control system enables the gunner or commander to lay and fire the main armament on the move.

Built-in new generation Duplet anti-tandem-charge warhead ERA protects against APFSDS, HESH and HEAT rounds.

The hull sides are hinged with large rubber skirts to withstand the attacks of man-portable anti-tank weapons.

The Oplot features a Varta optronic countermeasures system for deceiving incoming missiles and anti-tank guided weapons.

[2] Due to the collapse of Soviet Union, the Malyshev Factory was no longer able to obtain ceramic armour modules from Russia and only the initial batch of T-84 were produced with such.

Instead, later batches of T-84's composite armour is composed of special purpose rubber sandwiched between steel and alloy plates.

[citation needed] BM Oplot is powered by a 6TD-2E 6-cylinder turbocharged liquid-cooled engine, which delivers 1,200 horsepower (895 kW).

Either side of the six dual rubber-tyred road wheels are provided with idler at forward, drive sprocket at the rear, and track support rollers.

After successful completion of the extensive trials programme in the late 1990s the T-84 entered service with the Ukrainian Army in 1999.

[22] During the Russian invasion of Ukraine, at least one T-84 was deployed with the 3rd Tank Brigade in Donbas, near Barvinkove and Slovyansk.

[24] In March 2011, the Royal Thai Army placed an order for 49 Oplot-T to replace its fleet of aging M41A3 Walker Bulldog light tanks.

In September 2011, the Malyshev Plant announced plans to produce the first batch of five Oplot-T tanks for the Thai Army by the end of the year.