The T-28 was the main medium tank serving in the Red Army during the 1930s and remained in production until shortly before the USSR's entry into World War II. Inspired by the British A6 and designed as a breakthrough tank, the T-28 was extremely well armed for its time thanks to a 76.2-mm KT-28 gun that was far more powerful than any other fitted on a medium tank in the 1930s. Armor protection was also a priority and to this end it featured a maximum of 80mm in its later variants. Like the T-35 heavy tank which it strongly resembled, the T-28 was a multi-turreted design, which aside from the main gun also had two movable machine guns. This required two extra crewmen (for a total of six) and proved to not be particularly effective. All units were also equipped with a two-way radio in the form of a frame aerial around the top of the main turret. Another visual characteristic were the prominent mud chutes that doubled as side skirts for the multi-wheel suspension. The T-28 first saw combat against the Japanese in 1939 and later, in the 1939-40 Winter War against Finland. During this conflict, they became renowned for their performance during the breakthrough of the Mannerheim Line in 1940. By the time of the German invasion in 1941 it remained in widespread service with the Red Army and was in action during the first few months of the conflict before being gradually replaced by its successor, the T-34.

Development of the T-28 began in 1932 and it was originally fitted with a 45-mm Model 27/32 gun before being replaced by the short-barreled 76.2-mm that became standard. The T-28A was the first improved variant which featured a modified suspension with 12 bogie rollers with four return rollers and thicker frontal armor. This was followed by the T-28B with a ball-mounted machine gun in the rear and a longer caliber L-10 (L26) gun. Attempts to improve protection during the war against Finland resulted in the T-28C with frontal armor increasing from 50mm to 80mm and thicker armor on the sides and rear as well. This version was used in the 1940 breakthroughs. The last dozen units produced used the same conical turret as late T-35s. The chassis of the T-28 was also adapted for numerous uses including various experimental variants along with the IT-28 bridelayer and a mine-clearing tank.