What prevented the Soviet Union from making a treaty with Western democracies against the Nazi threat?
Fascism was more closely aligned to Communist goals than democracy, so Italy seemed a better ally.
The Nazis promised to avoid invasion, while democracies made no such promise.
The Soviet Union had little to gain from Western democracies, so there didn’t seem to be an advantage.
They tried, but Western nations were suspicious of the threat of Communism.