The American Army wanted to station observers with the Russian Army to learn German tactics and equipment, but Stalin firmly he refused. He also refused to support shuttle bombing of Germany by British or American air crews flying out of Britian and landing in Russia and then again on the return trip, much less stationing American Air Forces in Russia, as the American wanted.
Stalin feared that Russians would become friendly with Americans, upsetting the negative view of Americans he and the party were carefully cultivating.
And after the German surrender, Stalin sent all Red Army soldiers who met with and smoked cigs with, etc, Allied soldiers, into re-education camps.