S. soil becomes a virtual certainty; already, renowned experts like Graham Allison (2004) consider this a matter of when not if. Ironically, given the complexities of the primary military threats of the Cold War, the U.S. now faces much greater risk of a devastating nuclear attack detonated in a U-Haul trailer crossing a Manhattan bridge, or one spanning the Potomac than one employing high-tech missile guidance systems launched by another global power (Allison, 2004). Options for Addressing the Threat of a Nuclear Iran:

There is virtually no doubt that were the U.S. located within the range of Iranian missile technology, we would be as committed against allowing Iran to pursue its nuclear ambitions. In all likelihood, Israel's vulnerability in this regard is such that they will have no choice but to lead an attack designed to destroy the main nuclear facilities in the Iranian program whether or not the U.S. participates, sanctions, or provides direct assistance for such an attack.

However, unlike the Iraqi nuclear reactor destroyed by Israel in Natanz, the Iranian nuclear network comprise hundreds of individual facilities located underground in hardened bunkers and spread out throughout much of the country. It is, therefore, possible that without U.S. tactical assistance, Israel might eventually have only one option for preventing Iran from developing nuclear weapons: namely, a pre-emptive nuclear strike of its own. Given the inevitable blame that the U.S. will share throughout the rest of the Muslim world for such an attack, even without direct U.S. involvement, it might behoove this country to provide assistance to enable Israel to destroy the threat using the latest U.S. conventional (i.e. non-nuclear) technology capable of achieving the objective without the unavoidable death of millions in Iran.

However in all likelihood, the geopolitical effect on the U.S. would be comparable either way, except that without U.S. assistance, there is substantially greater chances...

subsequently.
Therefore, since (1) Israel is virtually certain to attack Iran to destroy its nuclear capabilities before they produce weapons-usable fissionable material; (2) the risk to the U.S. will probably increase thereafter if the Israeli attack is anything less than completely successful; (3) unrestricted Iranian fissionable material will be susceptible to transfer to terrorists like Osama bin Laden intent on attacking the U.S. with WMDs as soon as technically possible; and (4) the relative impossibility of preventing such an attack once sufficient quantities of weapons-grade nuclear material reaches terrorist hands, the U.S.

I would seem more at risk by virtue of allowing Iran to continue furthering its nuclear aims than by the consequences of a pre-emptive attack beforehand (Larsen, 2007).

Without a doubt, the U.S. military is already stretched beyond its long-term operational limit; any attack on Iran will severely damage U.S. foreign relations and the U.S. economy; and cause a tremendous amount of collateral damage (i.e. civilian casualties), Ultimately though, the consequences of doing nothing will be even worse, because any nuclear material diverted from Iranian programs destined for use on American soil.