Tupolev Tu-4

The Tupolev Tu-4 (NATO reporting name: Bull) was a piston-engined Soviet strategic bomber that served the Soviet Air Force from the late 1940s to mid-1960s. It was a reverse-engineered copy of the U.S.-made Boeing B-29 Superfortress.

Tupolev Tu-4 in Joe Steele
During World War II a number of B-29s that were damaged during raids on Japan flew on to nearby Soviet territory rather than return to base. These aircraft were copied and were used as a basis for the design and manufacturing of Tu-4s. During the Japanese War several Tu-4 bombing raids were launched by North Japan against the South. These were ineffective and soon stopped. On August 9, 1949 a sole Tu-4 flew over Nagano unchallenged and dropped an atomic bomb on the city in retaliation to the U.S. destruction of Sendai three days earlier with a similar weapon. This action effectively ended the war.