The SB 2M-103U is a modified version of the Soviet high-speed front-line bomber, the SB-2 (also known as the ANT-40), which was developed by the Tupolev Design Bureau and is its the most mass-produced aircraft. This version features a new liquid cooling system for the M-103A engines in the form of regulated air ducts. The SB 2M-103U was produced in the second half of 1939. Various versions of the SB 2M participated in the Spanish Civil War, the Sino-Japanese War, the Soviet-Finnish War, and the early stages of the Great Patriotic War.

The SB 2M-103U was introduced before the beginning of the open beta test. The aircraft's primary use is bombing. Despite its low rate of climb and poor maneuverability, it is capable of reaching speeds higher than those of pre-war aircraft, and it has three ShKAS machine gun turrets that reliably protect the bomber.