What's it for? I mean even if you believe in a genocidal deterrent, the one invented to square up to the USSR is hardly relevant to a totally different situation.

As for some imagined threat from Iran, so far as I know Iran has never invaded anyone in the last two thousand years, unlike a few other countries who might claim to have "a peace-loving group of people" controlling their government. And if we need it, how come Iran wouldn't have a much stronger case for needing it? Surrounded by hostile countries armed with nuclear weapons, and recent histories of engaging in invasions and occupations...