The T-80UD "Bereza" (Береза, "Birch") is a development of the famous T-80U main battle tank. The T-80U was intended to be a high-tech, high-performance MBT for the Soviet ground forces, featuring advanced fire control systems, strong protection, and high mobility courtesy of a compact but powerful gas turbine engine. However, the latter proved to have notable flaws in service such as poor fuel efficiency, and Soviet planners were interested in an alternative model with a diesel engine. The T-80UD emerged in 1985 with a 1,000 hp 6TD opposed-piston diesel engine originally designed as an upgrade for the T-64 and entered service alongside its turbine sibling before the fall of the Soviet Union. After 1991, as the design bureau and factory responsible for the T-80UD were located in the former Ukrainian SSR, the T-80UD served as the basis for a number of new tank designs in the Ukrainian T-84 family.

Introduced in Update "Alpha Strike", the T-80UD is effectively a downgraded T-80U. It looks nearly identical from the front aside from minor details such as the mudflaps and the arrangement of the turret roof ERA, but from the rear it's clear that the engine compartment takes after the fellow opposed-piston-engined T-64s. The replacement of the GTD-1250 turbine results in a noticeable drop in mobility from 27 hp/ton to about 22, not even matching the older T-80B, but it's still more mobile than the T-72B. It also has not been provided thermal optics or the top 3BM46 "Svinets" APFSDS. In other regards it is essentially still a T-80U, and its lower battle rating puts it on par with the T-72B where its strong armour, fast reload, and decent mobility make it a competitive option for the battlefield.