[TheCoelacanth]

First of all, Russia wouldn't have had a prayer without the non-Russian parts of the USSR.

The USSR could maybe have done it without help from ground combat troops from other countries. They definitely couldn't have done it without any help at all.

Without the UK's navy cutting off Axis shipping and without aerial warfare against the UK eating up a huge amount of resources, there would have been far more resources committed to the war against the USSR. Without lend-lease from the US, the USSR would have had extreme shortages of equipment.