The T-90 uses the same but slightly modernized gyro stabilized 125MM smoothbore tank gun as featured on T-72 and T-80 - 2A46M-2. This gun also allows to fire anti-tank guided missiles – mainly AT-11 Sniper an AT-11 Sniper-B. 43 rounds are carried for the main gun of the tank: 22 of them are installed on an automatic loading carousel and 21 in the non-mechanized niches.
The T-90's basic armor is a combination of composite and metal materials sandwiched together. The T-90's second tier of defense relies on explosive reactive armor (ERA) of the last generation named “Contact-5”. It consists of two armor plates with an explosive charge core sandwiched in-between. This type of armor works against a multitude of attack weaponry, including missiles and rockets that carry high explosive anti-tank warheads, as well as the dreaded sabot round.
The T-90 is powered by 12-cylinder supercharged, liquid cooled diesel engine with maximum capacity of 1130 horsepower depending on modification.
T-90 MBT as a basic model is only present in the Russian Ground Forces but its export modifications such as T-90S and T-90SA are operated by Indian, Algerian and Turkmenian armies as well as in Uganda and Azerbaijan.
Some sources in the Eastern Ukraine claimed that T-90 were noticed in Lugansk Region in July 2014 and participated in the battle for Lugansk airport.