On the first night of this week’s Democratic debate, one of the hopelessly interchangeable moderates accused the Trump administration of “lurching from one international crisis to another.” Since that’s the liberal consensus, neither the various fact-checking sites nor the blue-check Twitterati pushed back.

Yet it’s far from true. President Trump hasn’t, in fact, pursued disorder for its own sake. What he has done is to discard various false foreign-policy dogmas — mostly to salutary ­effect.

Witness this week’s US sanctions against Iranian Foreign Minister Javad Zarif. The New York Times waxed predictably apoplectic in a news story: “With Mr. Zarif sidelined,” the paper fretted, “it was unclear who else might serve as an experienced intermediary for Tehran in any potential talks.”

The administration imposed the sanctions on the ground that Zarif is little more than a propagandist for Tehran’s aggression and nuclear defiance — putting a slick, smiling face on the regime’s hideous policies.

Why is that useful? Because it means Washington will no longer abide by the ­fiction that the ­Islamic ­Republic is a normal government, with a normal foreign minister who carries out the will of that ­government and the people it represents.

That was the premise behind the Obama administration’s dealings with Zarif. When Team Obama negotiated the nuclear deal, it did so on the pretense that the man sitting across the table represented a real center of power in Iran — when in fact Zarif is nothing but a factotum in a system dominated by the unelected ­supreme leader and the Islamic Revolutionary Guard Corps.

If Zarif’s diplomatic smile were genuine, you would think the regime would have refrained from humiliating the United States while the ink on the ­nuclear deal was still wet. But that isn’t what transpired.

As Secretary of State Mike Pompeo told me in a phone ­interview last week (before the sanctions on Zarif were made public), “even during the ­[nuclear deal], they took our sailors and forced them to their knees” — referring to the Iranian seizure of two US Navy vessels in the Persian Gulf in January 2016, just a few months after the nuclear deal was signed.

He might also have mentioned Iran’s ballistic-missile tests that came soon after the accord was reached — almost as if the regime were bent on making a mockery of the superpower that had just bent over backward to win its ­nuclear concessions.

By treating Zarif for what he is — a frontman for a terror ­regime — Washington is now in essence telling the ayatollahs that we have their number.

At the same time, Team Trump has so far avoided a full-on ­kinetic confrontation in dealing with Iranian provocations in the Gulf. “We didn’t completely stand down,” Pompeo noted. “There were responses” to Iran’s downing of a US drone in June “that were not completely diplomatic. President Trump will ­respond with the level of force that is necessary, but it’s not useful to take action just for the sake of taking action.” (Those who accuse Trump of sowing chaos should contend with the fact that he is the first president in two decades who hasn’t launched ­regime-change wars.)

“Our strategy is now in place at full scale,” Pompeo said, noting that the administration anticipated the Iranians lashing out in response to sanctions and other pressure from the United States. Yes, “Khamenei and [Revolutionary Guard honcho] Qassem Soleimani are taking actions that pose real risks to US interests,” Pompeo admitted. “Our strategy has been to strangle their terror machine” — including, now, the chief propaganda mouthpiece of that ­machine, a k a Javad Zarif.

And it isn’t Iran policy alone that has benefited from this kind of hard-nosed realism.

Trump dropped the fantasy that the Golan will somehow ­revert to Syria and that Jerusalem won’t be Israel’s capital — and flames of Arab anger didn’t consume the Middle East, as critics predicted. He has dealt with China as a civilizational threat and sought to quarantine it out of the free-trade system — and the US economy hasn’t crashed and burned, as critics predicted. He has pulled out of various odious, anti-Israel UN agencies — and been vindicated as those agencies have discredited themselves and/or been mired in scandal.

Yes, Trump can be uncouth on the world stage. But better that than a president who worries more about preserving polite fictions than serving the nation’s interests.

Sohrab Ahmari is The Post’s op-ed editor. Twitter: @SohrabAhmari