George Will’s column on Iran gets many things right, but he makes this odd assertion towards the end:

The agreement will not stop Iran from acquiring nuclear weapons; only a highly unlikely Iranian choice [bold mine-DL] can do that.

It’s true that the interim agreement already reached in Geneva won’t “stop” Iran if the Iranian government chooses to violate the terms of the agreement, and that is also true for any comprehensive agreement that Iran and the P5+1 reach. Then again, that’s true of all diplomatic agreements: they become useless if one party ignores its commitments. Having said that, the evidence suggests that the Iranian government has so far not yet chosen to build nuclear weapons, and under the right conditions it may never decide to do this. An Iran that possessed nuclear weapons could be deterred, but if Iran follows through on the initial commitments made in the interim deal it is not going to build any nuclear weapons. In other words, Iran claims to have already made the “highly unlikely choice” that Will thinks it won’t make.

Will presents war and containment as the only two options, but it is more accurate to say that the U.S. would be able to contain a nuclear-armed Iran with or without first attacking it. War with Iran would not eliminate or even reduce the possibility of a nuclear-armed Iran, but would virtually guarantee it. Attacking Iran would give Iran a strong incentive and significant political cover to acquire nuclear weapons, which is why it is extremely misleading to talk about an attack on Iran as “preventive” war. “Preventive” war against Iran would likely cause rather than prevent Iran’s acquisition of nuclear weapons. The real choice is between reaching a negotiated settlement with Iran that limits its nuclear program in a way that makes weaponization much more difficult and continuing on the dead-end path of coercion and threats that make both a nuclear-armed Iran and armed conflict with Iran more likely.