Instead of worrying about the foreign policy chops of Heather Nauert, President Trump’s nominee for America’s next United Nations ambassador, critics may want to examine the ever-diminishing returns for America’s interests at Turtle Bay.

The usual suspects jumped at Ms. Nauert’s throat the minute Mr. Trump tapped her to succeed Nikki Haley. Mostly critics assailed Ms. Nauert’s relative diplomatic inexperience, while sneering at her previous job as host of a morning show on Fox News.

So far, so familiar. When Mr. Trump named Governor Haley as his ambassador two years ago, United Nations denizens and Acela-corridor highbrows mocked the South Carolinian for — you guessed it — lack of foreign policy experience. Yet Mrs. Haley emerged from the UN as arguably the most admired member of the administration.

The same pattern is playing out again with Ms. Nauert, only with a stronger hint of misogyny. Yet the charge of amateurism is belied by Ms. Nauert’s depth of international ­experience, which goes back before Mr. Trump appointed her State Department spokeswoman in April 2017.

As Jonathan Wachtel, a veteran TV producer who worked with Ms. Nauert at Fox, told me, “We traveled together to hotspots such as Darfur and South Sudan. We worked on international stories about the Middle East, Asia, Europe and Latin America — you name it. If you want to understand the issues, there’s no substitute for seeing things on the ground, which Heather always tried to do.”

As Mrs. Haley’s communications director, Mr. Wachtel also worked closely with Ms. Nauert when she arrived at State. “She’s had a combination of first-hand field experience and deep-dive training from experts and veteran service officers at the State Department,” he says. Among other assignments, Ms. Nauert traveled extensively with Secretary of State Pompeo and was in his inner circle at crucial meetings, including on three trips to North Korea.

Incidentally, it was the “inexperienced” Mrs. Haley who set the stage for those trips to the Hermit Kingdom. President Trump’s diplomacy with Kim Jong Un was made possible mostly because Mrs. Haley managed to unite the Security Council behind tough sanctions.

She did that by telling council colleagues that unless they imposed punishing measures, Mr. Trump would go ape in Asia.

You can only pull that trick once, and here Mrs. Haley’s tenure at the UN holds lessons for her successor.

One main goal for Mrs. Haley was to combat United Nations bias against Israel, but it was an uphill battle.

“The tide has changed,” Mrs. Haley said recently while lighting Hanukah candles at a United Nations hall, one of her last major acts as envoy to the world body. Earlier that day, a majority of 87 countries voted for her General Assembly resolution to condemn Hamas terrorism. Yet the Arabs defeated the resolution with a parliamentary trick.

Worse: To “balance” Mrs. Haley’s proposal, Ireland added yet another anti-Israel resolution to the 20 the assembly automatically issues against the Jewish state every year. So much for that.

The United Nations’ problems go far beyond Israel, of course. Secretary Pompeo on Wednesday urged the Security Council to keep intact an embargo against Iran’s arms trade. To endorse the nuclear deal, the council had agreed to remove the embargo in 2020. Ballistic-missile restrictions will similarly expire in 2022.

Mr. Pompeo knew Iran has strong allies in the council, chiefly Russia and China. For some European powers, meanwhile, protecting the nuclear deal trumps curbing Iran’s misbehavior. Even a Meternich-like diplomat couldn’t get the council to toughen up on Iran.

So America will “be relentless in building a coalition of responsible nations who are serious” about confronting the Tehran regime, Mr. Pompeo told the council.

Translation: We’ll work with allies outside the United Nations, because even some of our European allies are unlikely to play ball.

No wonder Ms. Nauert — like many predecessors in GOP administrations but unlike Mrs. Haley — won’t be a cabinet member: The UN’s utility for America is limited.

Contra her critics, then, Ms. Nauert is far more credible than the institution she’ll soon join. She’s steeped in the issues and a talented communicator. So she’ll do fine. But if she wants to distinguish herself as a U.N. ambassador, she’d best throw all she has at reforming the institution — or at least minimizing the harm it can do us, our allies and interests.

This column first appeared in the New York Post.

Image: United States Department of State via Wikipedia.