(If anyone needs reminding of the alternative, North Korea has nukes. Iran does not — and is now further from one than it was. One of the extraordinary aspects of Trump’s caprice is his apparent willingness to open a second nuclear front, like some loony generalissimo who wakes up feeling an Asian conflagration is insufficient, a Middle Eastern one is needed, too.)

Thanks to Dexter Filkins at The New Yorker we have a verbatim account of Secretary of State Rex Tillerson’s first encounter last month with the Iranian foreign minister, Mohammad Javad Zarif. Tillerson is an ineffective secretary of state whose major contribution to truth-telling has been to call his boss, Trump, a moron. Still, as long as he’s around, he’s beholden to the Trump line on Iran, whatever his own reservations.

So Tillerson tells Zarif: “No one can credibly claim that Iran has positively contributed to regional peace and security.” This is true, but irrelevant to the nuclear deal. He tells Zarif that lifting sanctions under the accord “has enabled Iran’s unacceptable behavior.” This is untrue and so by definition irrelevant. He says of Iran and the United States, “the relationship has been defined by violence — against us.” The violence has gone both ways, and this is irrelevant.

Bait and switch: Imagine if Iran said it planned to rip up the nuclear agreement because the United States elected a Saudi-loving, Iran-hating president in Trump; and his dancing with the Saudi royals, combined with his Qatar derangement syndrome, had not “contributed to regional peace and security.”

Filkins writes of the encounter: “An aide to Tillerson later told me, ‘It was one of the finest moments in American diplomacy in the last fifty years.’ ”

I am paid to produce words. I regret that this sentence renders me speechless.

Of course, a Trump refusal to certify may not unravel the deal, but it would put it on life-support, as well as doing lasting damage to American credibility.

The Republican-controlled Congress may not reimpose sanctions — a step that would kill the accord — or take other legislative action to scuttle it, but Trump will already have done enough damage to make any nation question why it should conclude a deal with the United States. Only Trump could contrive to cede the moral high ground to Iran.

Trump will also have made the Middle East more dangerous, reinforced Iranian hard-liners, angered allies and done a disservice to Israeli security. He is in a class of his own.