Despite being allied to the Soviet Union during the war, the United States refused to send them any B-29s and ordered pilots of B-29s not to land in the Soviet Union. In spite of this, three planes were forced to land in the Soviet Union. These planes' crews were sent home, but the planes were kept and the Soviet leader, Stalin, ordered them reverse engineered to the smallest detail. His orders were so strict that the Soviet engineers were afraid to make any changes in the design, even when they found flaws.
In the late-2260s Captain James T. Kirk used the story of the Soviets reverse engineering the B-29 as an explanation of why Berlis Aknista's control of other people's minds didn't allow for advisers, only followers. (TOS novel: Troublesome Minds)