During the third Republican primary debate last week, by many accounts former United Nations Ambassador and South Carolina Gov. Nikki Haley gained some momentum in pursuit of distant second place in the race to overtake former President Donald Trump.

Haley is articulate, self-assured, photogenic and feisty. She undoubtedly was speaking for other candidates on the stage when, in a triumph of snark, accuracy and pith, she dismissed the increasingly insufferable Vivek Ramaswamy: “You are just scum.”

Among the candidates, Haley probably has the best bona fides on foreign policy, based on her two years as U.S. ambassador to the United Nations. By my rough calculation, some two-thirds of last week’s debate was connected to foreign policy — Israel, China, Ukraine, Mexico — giving Haley a bit of a home-field advantage.

So it was a head-scratching moment when, at about an hour and 28 minutes into the debate, she smirked, chuckled, rolled her eyes and said, “I don’t care what my colleagues at the United Nations think.”

Of course, it’s unfair to characterize a candidate by an uncharacteristic, offhand remark taken out of context. At 38 minutes into the debate Haley acknowledged the necessity of partnerships with other like-minded nations in a dangerous world. She said: “America can never be so arrogant to think that we don’t need friends. After 9/11 we needed a lot of friends.”

Still, Haley’s eye-rolling dismissal of her U.N. colleagues’ good opinion reflects a motivation worth noting: political candidates’ compulsion to talk tough about foreign policy in ways they could never do if they were actually in office.

The question that prompted Haley’s remark was related to an idea that several Republican candidates seem to embrace: sending U.S. Special Forces into Mexico to take out the drug cartels, even without Mexico’s knowledge or permission.

During the debate, Ron DeSantis was ambiguous on this subject, but when asked in August if he would support sending special forces into Mexico, he was clear: “Yes, and I will do it on day one.”

Haley was equally emphatic: “We’ll send special operations in to take out the cartels. We need to go to where they’re distributing it, where the supply centers are, and take them out.”

Don’t believe either one of them. This is the sort of campaign bluster that generally works on the hustings but would never survive the legal, political, ethical, practical and diplomatic complications that would obstruct such an action should the candidate ever actually make it to the Oval Office.

Other sorts of equally useless bravado were evident, as well. When asked what advice he would give to Israeli Prime Minister Benjamin Netanyahu about the war, DeSantis said, “Finish the job once and for all with these butchers Hamas … Hamas should release every hostage and they should unconditionally surrender.” In response to the same question, Haley said, “Finish them, finish them.”

But how?

The candidates were equally belligerent about Iran. Sen. Tim Scott demanded a “strike” on Iran: “ … cut off the head of the snake and the head of the snake is Iran.” Haley said, “ … take out their infrastructure … punch them hard.”

And what would happen if we did?

This sort of casual belligerence is probably useful during the campaign, but I hope the candidates — and the voters — remember that the actual president doesn’t have the luxury of rolling his or her eyes contemptuously at the opinions of the rest of the world.

The president simply cannot send troops into Mexico. He cannot advise Netanyahu to “finish them,” without considering the practical feasibility of a military solution. He has to placate Israel, an outraged ally, without dismissing the aspirations of desperate, stateless Palestinians. He has to somehow balance the atrocities committed against Israelis with the devastation of innocent civilians in Gaza.

This treacherous tightrope has to be crossed above an abyss that threatens a much larger war. And in the background lurk the nuclear powers, Russia and China. A serious escalation is just a careless misstep away.

All of these complexities should be obvious; they were completely absent from the debate stage last week.

John M. Crisp, an op-ed columnist for Tribune News Service, lives in Texas and can be reached at jcrispcolumns@gmail.com.