In 1944, the USSR quickly realized that in terms of modern heavy bombers they were lacking behind. When reaching Berlin, they noticed that Britain and America air forces had been constantly bombing German cities at capacities that the USSR did not have. Luckily, on the other side of the world, America had been bombing Japanese islands and some of their pilots had run into difficulty.
Instead of risking the return to their base, these bombers decided it would be safer to land in Vladivostok in Russia. The USSR was at this time still neutral in the war against Japan and therefore Stalin ordered for these planes to be impounded. He then realized that it would take over 5 years to design and manufacture their own heavy bombers, so why not just copy the B-29? He gathered his engineers and advised them they had two years to make this happen.
Two years was already a pretty extreme deadline, but no one at the time wanted to disappoint Stalin. In fact, there are several stories that came out of the engineering of what was called the Tupolev TU-4 which when you look back at them are quite funny.
First, they discovered a small hole in the left wing of one of the B-29, it was probably a bullet hole or maybe even a small drill hole that was done by mistake. The Soviet aerodynamic engineers had no idea what it was for, yet due to Stalin’s orders decide to implement it in their design. So every TU-4 that was built had a small hole in its left wing!
Another discussion was held over the Americans white stars on the wing, surely Stalin did not want these to be copied? No one wanted to disappoint his orders though, and they thought potentially it was a camouflage tactic! So they asked a top-ranking general to check with Stalin himself what colors they should make the stars, he apparently burst into laughter.