if the US and Israel did attack Iran all those younger generations of Iranians who look up to the west would be turned against the US and western civilisation and we would have more enemies in the future.
I agree that nuclear weapons up until now (with the exception of WW2) have stopped war and saved lives. the reason we haven't had another world war since 1945 is because all the great powers had nuclear weapons and nobody was game to set one off.