So far, in forging a strategy for handling this uncertain moment, Rouhani’s characteristic prudence seems to have won out. Even as economic pressure from America hits home, Tehran has held up its end of the nuclear deal, with perfunctory appeals for Europe to offset American sanctions with measures to protect and increase trade and investment that all sides tacitly recognize will not be forthcoming. Iran’s leaders have issued a barrage of thinly veiled threats aimed at Persian Gulf transit routes, but as Trump himself boasted, even here there is evidence of newfound restraint by the IRGC naval forces.

All of this might suggest that Trump’s pressure has created an unexpected equilibrium, forcing Tehran into an increasingly perilous impasse, lacking effective recourse and restrained by its own fears of a further deterioration. Unfortunately, that balance is unlikely to hold. The Islamic Republic is in the fight of its life, and steeped in a strategic culture that rejects weakness as an invitation to further attack, neither its leadership nor its military command is likely to go down quietly. “Be careful,” both Trump and Zarif have tweeted. Unfortunately, neither Washington nor Tehran is heeding those warnings.