I think well over 100 million people would have died if the US could have attacked the USSR in conventional warfare, if nuclear weapons had never been invented; actually, I think the USSR would have overrun Europe, the US would have been driven back, and communism would have had even more victims to feast upon.
A nuclear armed Iran is inevitable, IMO. The only means of trying to stop it - bigger and bigger threats, short of invasion no-one has the stomach for - seem to me to only guarantee this, because they reinforce the motivation for getting there.
Less than 100 million people died in WWII, and Russia had fewer allies after WWII than Germany did. Civilians killed totaled from 40 to 52 million, including 13 to 20 million from war-related disease and famine. Total military dead: from 22 to 25 million, including deaths in captivity of about 5 million prisoners of war.
Let's put this in perspective. At the end of WWII America was producing 50% of the WORLDS manufactured goods. Russia had fewer allies, a vastly inferior conventional Army, and infrastructure from WWII all the way to it's fall. America has had sufficient nuclear weapons to be concerned about a large scale invasion and never really geared up for a large scale war. So, America had basically no reason to attack Russia or fully mobilize as long as the rest of the world did not become communist they had little interest in what happened.
However, after WWII Russia was paranoid with good reason. http://en.wikipedia.org/wiki/File:World_War_II_Casualties2.s... Close to 13% of their population had just died and they had little interest in being so weak that a country could decide to attack them while in the middle of a war with several other countries.
A nuclear armed Iran is inevitable, IMO. The only means of trying to stop it - bigger and bigger threats, short of invasion no-one has the stomach for - seem to me to only guarantee this, because they reinforce the motivation for getting there.