From: Manchester, UK
Joe wasn't going to attack. The south faced weaker German forces (when compared to the ground to be fought over, had more ground to run into and was in parts much better led.
The Soviets certainly had plans for a pre-emptive strike on German forces massing in the east, but then the Pentagon will have plans for a pre-emptive strike on Syria. However, having them is not evidence of a political will to use them. You could argue the Ukraine did well from reinforcements and troops given its importance resource wise to the Soviet Union, but there is only mild circumstantial evidence Stalin was preparing an attack.
I don't doubt he felt he would have to fight Germany sooner or later, but I think the collapse of France threw his plans into chaos and led him down the appeasement path he seems to have adopted. I think he anticipated the Germans and Western Allies cutting each other's throats for a couple of years before he swept over the border and shared the spoils of a defeated Germany circa 1942. By that point his reorganisation of the Army following the finnish debacle and late 30s purge would have been complete and he would have been ready.
As it was, when France fell, he knew he wasn't ready, so he did his utmost to avoid a fight, ignoring all evidence the Germans were preparing to invade, refusing to fire on heavy recon, feeding them trains packed with resources upon request etc.....