Count it as one campaign promise we’d rather President Trump hadn’t kept, at least not the way he seems to be doing it.

Out of the blue, the White House sent word Wednesday that the US is withdrawing its forces from Syria, with all 2,000 to be out “as quickly as possible.” US diplomats in Syria are already being evacuated.

That move doubtless will leave the rulers of Iran and Russia and the leaders of ISIS smiling. Elsewhere, it’s raising eyebrows — with good reason.

Because such an abrupt withdrawal is precisely the kind of mistake President Barack Obama made in Iraq — leaving an enormous vacuum for Russia, Iran and extremist groups to fill and abdicating any US influence in the area.

Trump tweeted that he made the decision because “we have defeated ISIS in Syria, my only reason for being there.”

But that’s not totally true: The so-called caliphate still controls some 2 percent of northern Syria and for months has resisted ongoing efforts to oust it completely.

That the move caught even top administration officials — who’ve long argued against such an abrupt move — off-guard seems clear from a speech Monday by the US special representative in Syria outlining a completely different policy.

The official, James Jeffrey, vowed the United States would stay in Syria until ISIS’ lasting defeat is assured, Iran’s influence is rolled back and a political solution achieved. None of those conditions has been met.

The withdrawal also undermines the US-backed Kurdish Syrian Democratic Forces, who have led the ground attack against ISIS but are threatened with imminent attack by Turkey, whose President Recep Tayyip Erdogan calls them a terrorist group.

That leaves the Kurds with little choice but to cut a deal with Assad — and, effectively, his Russian and Iranian allies. It’s also going to raise doubts among any similar groups about the value of US support.

Trump’s decision reportedly followed a phone conversation with Erdogan last Friday. Did the president let Erdogan’s hallmark bluster push him into a hasty decision?

President Trump was always committed to withdrawal from Syria as soon as feasible. But, as most of his senior security officials would agree, now is not that time.