President-elect Donald Trump. (Carolyn Kaster/Associated Press)

PRESIDENT-ELECT Donald Trump’s national security appointments — CIA Director-designate Mike Pompeo, future national security adviser Michael T. Flynn and South Carolina Gov. Nikki Haley, Mr. Trump’s choice for ambassador to the United Nations — differ with him or with each other on such crucial issues as relations with Russia and the civil war in Syria. But Mr. Trump and his appointees appear united on one point: antipathy toward Iran and the international deal limiting Tehran’s nuclear program.

During the campaign, Mr. Trump repeatedly described the 2015 accord as “a disaster” and suggested he would tear it up and “double up and triple up sanctions.” Mr. Pompeo tweeted just before Trump announced his planned nomination that “I look forward to rolling back this disastrous deal.” Mr. Flynn has said that “the U.S. gets nothing but grief” from the deal.

We supported the nuclear pact, albeit reluctantly because of its sunset provisions that will remove most controls on Iran’s uranium enrichment within a decade. In essence, it is a risky bet that the Islamic republic will lose its appetite for a nuclear arsenal during that time. But for the Trump administration to start by voiding the accord would be a curious inversion of priorities.

Since the bargain was struck, Tehran has aggressively pressed its bid for regional hegemony by other means — foremost by waging war in Syria on behalf of the regime of Bashar al-Assad. As The Post’s Hugh Naylor recently reported, the thousands of Shiite militiamen Iran has mobilized to fight there are setting the stage for Iran to dominate the country — much as the Hezbollah militia holds the balance of power in neighboring Lebanon. Iran is also backing Houthi fighters in Yemen against Sunni forces and seeking to challenge U.S. warships in the Gulf of Aden and the Persian Gulf.

Ripping up the nuclear accord will do nothing to address these aggressions. Instead, it will open a rift between the United States and the other parties to the deal. Britain, France, Germany, China and Russia will not reinstate sanctions on Iran unless it is shown to have violated the accord. So far, despite some minor transgressions, it has not. On the contrary, Tehran has reduced its stockpile of enriched uranium by 98 percent, placed two-thirds of its centrifuges in storage and disabled a reactor capable of producing plutonium. For the moment, there is little danger that it could or would attempt to produce a nuclear weapon; but if the deal is ruptured, it could begin to do so — forcing a Trump administration to contemplate war.

All this suggests Mr. Trump would do well to listen to retired Marine Corps Gen. James Mattis, another Iran hawk who is a leading candidate to become his defense secretary. Mr. Mattis was also critical of the nuclear deal because of its long-term risks, but in a speech this year he concluded “there is no going back.” The general pointed to five threats Iran poses: nuclear, challenges to shipping, ballistic-missile development, cyberattacks and terrorism. The nuclear deal has restrained one, even if temporarily. The Trump administration would be wise to focus on the others.