Embedded in any policy is some theory of victory—some explanation, no matter how inchoate or ill-considered, that explains why this might work. So too with President Trump’s decision to walk away from the Joint Comprehensive Plan of Action, the agreement with Iran so ungainly that even the acronym JCPOA seems elegant by comparison. The nominal theory of victory here is preposterous: that Iran will come to heel, retreat from its nefarious activities in the Middle East, end ancillary programs such as its ballistic-missile work that support the nuclear program, and permanently renounce its nuclear program in word and deed. Such behavior would be inconsistent with anything Iran has done in the past and would be a crushing humiliation that would jeopardize the very survival of the regime.
The real theory of victory, rather, is that American sanctions—to include those inflicted on European and other foreign companies doing business in Iran—will bring down a regime whose economy is already collapsing. That is the real test of the new lukewarm war with Iran. It is conceivable but unlikely that this will work. For now, the Iranian regime seems able to repress dissent as brutally as it wishes. That is how it survived the uprisings of 2009. Other actors (China and Russia most notably) have every incentive to prop up the Iranian regime if for no other reason than to demonstrate the limits of American power. America’s European allies will cooperate grudgingly with American behavior that most of them view as outrageous, and some of them may actively thwart or undermine American sanctions.