“The US was sort of stuck between a rock and a hard place because on the one hand, if it did not respond to this latest attack, considering that a US citizen was killed, it would have sent a pretty strong signal that the red line that it had laid out about US casualties didn’t mean anything,” said Ariane Tabatabai, a political analyst at the Rand Corporation.

By highlighting the Iraqi government’s impotence on its own territory, the retaliation diverted public dissatisfaction with the heavy-handed Iranian presence in Iraq, to the desire to be rid of the imperious Americans. The US comes out of this tit-for-tat round weaker and with fewer options.

It is not clear whether the US has a plan for what happens now. The campaign of maximum pressure was supposed to force Iran to accept a worse deal than the 2015 multilateral nuclear agreement on which Donald Trump walked out in 2018. The oil and banking embargo on Iran have been highly effective in damaging the Iranian economy, but have failed to make Iran bow to US demands for Tehran to give up its military stake in Middle East conflicts and its enrichment of uranium.