IRAN, LIKE the United States, is fighting a so-far failing war against the novel coronavirus, which according to expert studies could kill millions in both countries if it is not contained. Yet neither the Trump administration nor the regime of Ayatollah Ali Khamenei has let this unprecedented emergency distract them from their war against each other. Iranian-backed militias in Iraq have repeatedly launched rockets against U.S. targets this month, even as tens of thousands of covid-19 cases swamped medical facilities inside Iran.

The United States has responded by bombing the militias’ weapons storage sites and by continuing to escalate sanctions on the stricken Iranian economy; last week, several companies involved in marketing Iranian petrochemicals were targeted. This week, Mr. Khamenei and Secretary of State Mike Pompeo devoted themselves to overheated verbal broadsides: The Iranian ruler blamed U.S. sanctions for impeding the fight against the epidemic, which he hinted had been created by the United States, while Mr. Pompeo claimed Tehran was lying about the extent of infections and stealing money intended for medical supplies.

There is a certain crude logic to the attacks in Iraq: Iranian hard-liners have plausible hopes of forcing a U.S. withdrawal from the country and handing the regime a strategic victory to balance the losses inflicted by U.S. sanctions. But the strategy behind U.S. policy is harder to discern. At a time of an extraordinary humanitarian crisis, the Trump administration is stepping up “maximum pressure” measures that increase hardship for a nation of 80 million. To what end?

Neither the collapse nor the capitulation of the regime seems a likely result. Instead, the United States is being blamed by ordinary Iranians as well as other nations for making it more difficult for authorities to combat the epidemic. That includes allies: Britain is among those that have asked for an easing of sanctions.

Mr. Pompeo asserts that the United States has offered medical assistance to Iran — which the regime rejected — and that sanctions do not target imports of food or medicine. But U.S. measures to curtail Iranian financing, insurance and shipping surely have an effect. Writing in the New York Times, Narges Bajoghli of Johns Hopkins University and Mahsa Rouhi of the International Institute for Strategic Studies reported that several companies that supply medical equipment used to combat the coronavirus had stopped shipping to Iran.

President Trump has, at least, resisted pressure from Mr. Pompeo and other hard-liners to further escalate military action in Iraq. But instead of escalating sanctions, he ought to be offering Iran the chance to ease tensions through mutual humanitarian actions. The regime has already paroled one of the U.S. citizens it had been holding in its prisons. While seeking the release of the others, the administration should support Iran’s request to the International Monetary Fund for emergency aid.

The confrontation Mr. Trump initiated with Iran has manifestly failed to achieve its aims. The coronavirus epidemic offers him the opportunity to correct course while helping to contain one dangerous focal point of the pandemic.

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