A detailed diagrammatic poster prepared by the Ministry of Supply in April 1951, elucidating the specifications and design of the Tupolev Tu-4. The aircraft was reverse-engineered from four Boeing B-29 Superfortresses (three intact, one crashed) that the Soviet Union had interned in 1944 after emergency landings. To maintain a cordial relationship with their wartime ally, the United States did not make a concerted effort to have the B-29s returned and asked the returning airman, who had also been interned, to keep quiet. Andrei Tupulov, arrested in 1937 during the Great Purge and from 1939 to 1941 sentenced to work in an NKVD sharashka for aircraft engineers, was tasked by Stalin in 1945 with copying the design. It was an elaborate endeavor, requiring the work of, "some 64 design bureaus and over 900 factories, research institutes, and technical entities." Among the difficulties that arose was keeping to the B-29's imperial specifications with components made to metric specification.
The plane was first publically displayed during a flyover at Tushino Airfield near Moscow for the 1947 Soviet Air Fleet Day. Although the Tu-4s were never used by the Soviet Union in combat, they came close in 1956 when several were called to bomb Budapest during the Hungarian Uprising before the mission was aborted. In early 1953, before his death, Stalin gave 10 Tu-4 airframes to Mao as a birthday gift. China used the bombers in attacks on Jamchen Choekhor Ling in 1956. China received an additional two as navigational trainers in 1960 before Khruschev's withdrawal of aid in August of that year. After its development and mass production helped launch the Soviet strategic bomber program, the Tu-4 began to be replaced by the more advanced Tu-16 and Tu-95.
Conboy, Kenneth J.., Morrison, James. The CIA's secret war in Tibet. United Kingdom: University Press of Kansas, 2002.