The Soviets were definitely not in the position to invade German held territory in 1941 given that paranoid Stalin had just butchered most of the officer core in 36'-38'. The Red Army was a completely disorganized, poorly trained rabble in July 1941 - that's why they were absolutely decimated by the Germans during the opening months of Operation Barbarossa. Stalin, after ignoring Churchill's advice to prepare a proper defence against Germany, was reported to have suffered some sort of mental breakdown upon learning that the USSR had been invaded. He supposedly locked himself up in his dacha for three days refusing any telephone calls or visitors. If true, it really doesn't seem like he was prepared to go to war anytime soon.