The idea of a so-called 'nuclear deterrent' no longer applies – the United States would not be deterred from attacking a newly nuclear Iran because the U.S. would have a first strike capability so would be able to wipe our Iranian nuclear weapons before they could be used. While it is true that political leaders on both sides during the Cold War were terrified of a nuclear conflict it was as much the balance of power that maintained the peace. Neither superpower had an advantage large enough to be confident of victory. However, there is no longer nuclear deterrence. With the proliferation of nuclear weapons, some rogue states may develop the ability to strike at enemies who have no nuclear weapons of their own. Unless the country under attack is allied to another nuclear power It is not clear that any of the major nuclear powers would then strike back at the aggressor. This is further complicated by the fact that most of the emerging nuclear threats would not be from legitimate governments but from dictators and terrorist groups. Would it ever be acceptable to kill thousands of civilians for the actions of extremists?