Though negotiators had expressed concern that Trump was running low on final warnings, the White House has assured that there were more in reserve. "We are prepared to open our strategic reserve of final warnings," said one official. "No one wants to get down to a third-to-last warning, which includes a strongly-worded letter. But President Trump isn't afraid to unleash it."

At publishing time, Trump had announced that Iran had agreed to fresh negotiations and so was now back to its fourth-and-a-half-to-last chance.