Nuclear ICBM armageddon from Stalin would have been really cool - a bigger threat would be fun. Did he have initial visibility of our lands? 5E thought he wouldn't be able to launch until he knew where we were, so we were careful not to trade him any maps until we proved he only had tac nukes.
I think it was possible to estimate Stalin's military assets using the power graph numbers at the start of the game and the demographics. I wasn't the one who did the calculations though so I can't swear by this statement