What internal and external reasons caused the forced modernization in the USSR?

If we talk about modernization, the internal reasons for its acceleration were the fact that at that time the country was very far behind other more developed states. It was necessary to catch up with the Western countries, so modernization was forced. Another factor can be called the poverty of the population, and thus there were attempts to improve welfare.

An external factor can be called the fact that the country wanted to get rid of dependence on the part of Western states. Another factor can be called the desire for quick recognition by the UN countries.