In addition to increasing benefits of military options, the deal can reduce costs of action. One of the main costs of military action now is that it could cause the current sanctions regime to collapse, as a U.S. (or Israeli) strike would be seen as an act of unprovoked preventive war. The collapse of sanctions could benefit Iran immensely, particularly in terms of reconstituting its nuclear program. In contrast, if Iran is seen to be violating the deal through attempted breakout, sanctions are to be rapidly reinstated. In this case, military action would not be seen as a decision to give up on diplomacy. Instead, it would be seen as a response to Iranian violations of a diplomatic deal that already had the blessing of the United Nations. Indeed it might even be possible to get a U.N. Security Council resolution authorizing the use of force against Iran’s program in this context. Admittedly, given the Russian and Chinese vetoes it is unlikely. Thus the deal may be the only way to have internationally supported sanctions and the effective use of force simultaneously.

It is this combination that helps answer the end game question. If Iran is widely seen to be violating such a hard won (and relatively generous) deal by attempting breakout, the use of force can lead to an outcome that is catastrophic for Iran. Not only would Iran’s entire nuclear infrastructure, built over decades, be demolished but it could be diplomatically and economically more isolated than it is now. In this end game the balance of power in the Middle East would shift significantly against Iran and the regime could face significant unrest after having gambled and lost. This prospect should warm the heart of even the most hawkish.