> It's why the US entered WW1 and WW2 even if it didn't have to. Because if it didn't and just decided to sit it out chilling away from the conflit, it would have missed out on all the major industrial and technical progress the war effort has led to and the USSR would have swallowed everything.

The USSR was formed in 1922. Up until September 1917 (a consequence of the February revolution), Russia was ruled by the tsars. The US declared war on Germany on April 2, 1917.