Fears are mounting that a second-term Trump presidency would bring a rapid American retreat from global leadership. “If Trump wins, he will destroy the American-led world order,” a Washington Post column warns. “Europe worries U.S. isolationism is back,” the Post reported from the annual Munich Security Conference.

“If an isolationist Republican wins in 2024, it could mark a turning point for the US-dominated international order established at the end of World War II,” writes an official in the Clinton administration, Joseph Nye, Jr. Mr. Trump spoke Saturday at CPAC before a backdrop that said, “where globalism goes to die.”

Ironically, given that backdrop on the CPAC stage, Mr. Trump gave a foreign-policy speech. He began by acknowledging the dignitaries in the audience. They included the president of Argentina, Javier Milei. “He’s a great gentleman,” Mr. Trump said. “It’s a great honor to have him with us.”

The 45th president also called out, by name, the president of the Vox Party in Spain, Santiago Abascal. He welcomed a federal deputy from Brazil, Eduardo Bolsonaro, who is a son of the former president of Brazil, Jair Bolsonaro. Mr. Trump quoted the prime minister of Hungary, Viktor Orban.

Mr. Trump said that if he were president, America “would have never left” the Bagram air base in Afghanistan, which he said was one hour away from where China builds its nuclear weapons. He faulted President Biden for enriching Iran and said, “If I were president, Israel would have never been attacked.”

The GOP front-runner said that in a second Trump presidency, “We’re gonna be respected all over the world.” This was not the speech of an isolationist. It was a tour-of-the-horizon that might have been offered by a foreign-policy president such as Richard Nixon.

Some people might reply that Mr. Trump is merely talking that way to reassure nervous voters about his intentions. What he would actually do once in office is another matter. No speculation is needed, though. There is the first-term Trump record on which to look back.

During that first term, there were indeed some retrenchments. In 2019, Mr. Trump pulled some GIs out of northern Syria. In 2020, Mr. Trump announced plans to reduce the number of Yanks in Germany, and he also made plans to leave Afghanistan and Iraq. He also floated the idea of withdrawing from South Korea.

One can debate the merits of those adjustments, but they fell far short of a full retreat to Fortress America. At the end of the Trump administration, America was spending about 3.8 percent of its gross domestic product on defense and international affairs.

That level was slightly more than at the end of the Obama administration, but less than during the Reagan-era Cold War or the George W. Bush era Global War on Terrorism, according to the White House budget office. Even were Mr. Trump to propose a new or bigger round of strategic shifts, they’d be watered down by the status-quo oriented Washington press corps and bureaucracy.

As for Mr. Trump’s comment recounting a warning that if NATO allies didn’t spend on their own defense, America wouldn’t protect them from Russia, that is best understood as a negotiating tactic to urge Europe to shoulder its share of NATO costs, not as an invitation for Russian tanks to roll through Eastern Europe.

The full quote, as the Associated Press has it, makes that pretty clear: ““You didn’t pay? You’re delinquent?’” Trump recounted saying. “‘No I would not protect you. In fact, I would encourage them to do whatever the hell they want. You gotta pay. You gotta pay your bills.’”

Would a President Haley be more willing to send troops and money overseas? Probably. Yet she would also have to reckon with the isolationist right and left fringes in Congress. They, not Presidents Trump or Biden, pose the real isolationist threat.

Trump is striking a balance. His “America First” slogan appeals to Americans tired of “endless wars” who want money spent at home rather than abroad. Yet voters also know that a significant American pullback would come at a cost to American prestige and national security.

It would leave a vacuum that would be filled by enemies like Iran and Communist China. No digital backdrop declaring death to globalism will make those enemies magically disappear. No wonder Mr. Trump is already identifying potential international allies for a second term focused on restoring America’s global prestige.