Didn’t Stalin indeed support Hitler until he invaded the Soviet Union?
They signed a non agression pact 8 days before Hitler invaded Poland. Stalin invaded Poland and both Hitler and Stalin stopped advancing at a jointly agreed upon boundary.
https://en.m.wikipedia.org/wiki/Molotov–Ribbentrop_Pact
They sure looked like they were allies on May Day of 1941 (7 weeks before Operation Barbarossa began)
https://www.youtube.com/watch?v=jAfSrBMuXI8