What do you mean by private property? Do you mean that word in a Marxian sense? Or do you mean it in a classical/neoclassical sense and thus projecting non-Marx

What do you mean by private property? Do you mean that word in a Marxian sense? Or do you mean it in a classical/neoclassical sense and thus projecting non-Marxist economics on Marxist economics? No one believes that foreign investment is anything more than a necessary evil - being reliant on foreign investment means that you can't mobilize your own capital. The idea that markets are necessary for some industries is not at all incompatible with Marxist economics. Lenin's side of Marxist economics would be fine with markets as long as the property was owned cooperatively, until a post-scarcity society. Stalin's turn towards state planning was out of perceived necessity, not because he was less patient. He, and others in the party, decided that it was acceptable to sacrifice overall economic development in order to develop the heavy industries necessary for war with capitalist countries, that he thought was inevitable if they were too weak. That, and he thought agricultural development was too slow. While it was a failure for agricultural output, it was objectively a massive success in its primary goal, and development of heavy industries at the speed of the NEP would have probably led to the USSR losing WW2.