Are we really to imagine that the West will go to all the trouble of reimposing the UN sanctions because of one site that is enriching uranium illegally but nowhere near weapons-grade? Plainly the politics of the moment will matter. Theory and common sense, however, can help us make predictions. In my earlier column, I pointed out that a degree of cheating can be tolerated as long as the West’s overall gain from the deal outweighs the cost of Iran’s cheating. If the choice is between allowing this single illegal laboratory to go uninspected for a time and reimposing the entire sanctions regime, I would expect the West to blink. Indeed, it would be rational for the West to blink rather than wreck a deal that is in other respects working.

The trouble is that the West, in its focus on creating a mechanism for the snap-back of sanctions, has left itself without any other, lesser weapons. As several analysts have pointed out, there is the option to reimpose full UN sanctions … and nothing else. Remember that the parties, including the U.S., have undertaken not to enact any additional nuclear sanctions except through the process set forth in the agreement — that is, going through the Joint Commission and the Security Council. There is no way to impose small, measured sanctions for small, measured violations. This is what I mean when I say that room for cheating is built into the structure of the agreement.