It will be almost impossible to contain a nuclear Iran. Command, control, and custody over any future Iranian bomb will rest not among Iranian pragmatists, but rather within the most ideologically pure unit of the Islamic Revolutionary Guard Corps (IRGC). The vast majority of Iranians are moderate, cosmopolitan, and forward-thinking, but the concern of America policymakers must focus upon those whose fingers are on the button who may actually believe the Messianic rhetoric spouted by their leaders.
Should Iran go nuclear, it is doubtful the Iranian leadership will order a first strike on Riyadh, Tel Aviv, or regional American facilities. But, overconfident behind its nuclear deterrence, the IRGC will lash out. Export of revolution is the Islamic Republic's raison d'être, enshrined in its founding documents. When former President Mohammad Khatami suggested the regime interpret revolutionary export through a soft-power prism, senior clerics and Revolutionary Guardsmen shot him down. Rather than bring peace, a nuclear breakout will lead to a resurgence of terrorism and asymmetric warfare.
That the Iranian regime is not suicidal does not mean deterrence can work. In 1999, 2001, and 2009, Iran erupted in nationwide protests. After each instance, the IRGC restored order. The problem comes when, as in Romania 1989 and Libya 2011, security forces begin to join the protestors. If the most elite and ideologically pure IRGC elements know that their regime will cease to exist within 24-hours, then they may act out their ideological imperatives. There is some precedent: After Muammar Qadhafi's forces lost control of Tripoli, they launched SCUD missiles at the rebel-held city of Misrata for no other reason than sheer spite.
Multiculturalism is not simply about walking into a sushi restaurant and ordering a mojito. At its core, it is the recognition that different peoples think in very different ways. By ignoring the ideology of those in Iran who would actually control the bombs, the strategic logic of the Cold War falls flat.