During the 1930s most of the technology was developed internally. This was mostly due to the strained relations especially after the scare in 1928 when the Soviets feared British invasion due to a diplpomatic blunder. On the other hand it is true that many US citizens emigrated to the Soviet Union during the 1930s. This was mostly due to the new gorwing job market in the Soviet Union providing many more opportunities than the stagnating market in the US during the Great Depression.