Secretary of State Mike Pompeo grew testy in a recent newspaper interview when asked to explain why President Trump would take North Korean leader Kim Jong Un “at his word” about the death of a U.S. college student taken prisoner in North Korea.

National security adviser John Bolton, making the rounds of Sunday talk shows, flatly refused to offer his personal assessment of whether Trump’s summit with Kim — which ended early and without an agreement — had given the autocrat unearned leverage, even as Bolton broadly called it a “success.”

And Trump and his top trade adviser quibbled in front of reporters and Chinese officials late last month during an Oval Office meeting over how to describe the contracts that would form the basis of any trade deal between the United States and China.

Two years into a presidency that has upended assumptions about the U.S. role in the world and flipped the script on core Republican tenets such as arms control, ardent support for democratic principles and free trade, Trump’s national security officials and Republican allies are still struggling to defend or even explain the president.

“The party is silent on foreign policy for the same reason it’s silent on other issues: fear and trying to keep open lines of influence,” said former senator Jeff Flake (R-Ariz.), a Trump critic.

Trump’s foreign policy is part nationalist, part conservative, part isolationist, part militaristic pageantry. He distrusts traditional alliances such as the North Atlantic Treaty Organization and slaps punitive tariffs on adversaries and allies alike.

In many ways, Trump’s worldview has been boiled down to a mantra lacking labels and ideology: It is what Trump says it is.

After the second U.S.-North Korea summit came to an abrupt end on Feb. 28 in Hanoi, President Trump and North Korea had contradictory reasons for its collapse. (Joyce Lee/The Washington Post)

For the president’s supporters, that foreign policy is notable as much for what it opposes as it is for its own stances.

“Trump stands as a direct challenge to the postwar, international rules-based order where America gave an open-ended security guarantee,” former White House chief strategist Stephen K. Bannon said, adding: “This is not America alone, or America withdrawn or America indifferent. It’s America with allies, not protectorates.”

But arguing in favor of that singular style has proved easier from outside the administration than within.

Trump’s meeting in Hanoi last week with Kim was the capstone of his most significant foreign policy undertaking and his signature reliance on personal dealmaking over traditional diplomacy. The disappointing outcome left Trump to defend his approach and say progress remained possible.

But on Sunday, Bolton, who has been a skeptic of negotiating with North Korea, struggled when CBS moderator Margaret Brennan pressed him on whether he agreed with Trump that he had not given anything away to Kim at the summit.

“The president’s view is he gave nothing away,” Bolton repeated carefully. “That’s what matters, not my view.”

When trying to finesse Trump’s statements and negotiating stances, Pompeo has sometimes adopted a strategy of denial and redirection.

Late last month, ahead of Trump’s meeting with Kim in Hanoi, Pompeo was asked in an interview with CNN whether he agreed with the president’s tweet following last year’s Singapore summit that “there is no longer a Nuclear Threat from North Korea.”

Pompeo initially denied that Trump made the statement. Then, when read the tweet, he pivoted to saying the president said that the nuclear threat from Pyongyang has been “substantially taken down.”

In a weekend interview with USA Today following the meetings in Hanoi, Pompeo reportedly “reacted angrily” when asked about a North Korean official’s statement following the Hanoi meetings that the country will not change its offer to the United States — a statement that contradicted Trump’s rosier view of the summit.

“That’s not what the North Koreans said,” Pompeo said, according to the paper. “Don’t say things that aren’t true.”

Read the quote from North Korean Foreign Minister Ri Yong Ho — “Our principal stance will remain invariable and our proposal will never be changed, even though U.S. proposes negotiation again in the future” — Pompeo paused, according to the paper, before saying the North Koreans said they were prepared to continue conversations with the United States.

Even Trump’s trade negotiator, Robert E. Lighthizer — who shares Trump’s fondness for tariffs and willingness to discard traditional Republican free-market principles — found himself getting schooled in front of senior Chinese officials in the Oval Office.

“To me, the final contract is really the thing, Bob, and I think you mean that, too,” Trump said as Lighthizer nodded after a brief public disagreement between the pair. Lighthizer had described an aspect of trade talks as a “memorandum of understanding,” a phrase that Trump said he disliked but that is a common practice in trade deals.

Part of what vexes Republicans is Trump’s unpredictability and insistence on relying on his gut impressions. Several former aides said this side of Trump’s foreign policy was cultivated during the early days of the 2016 campaign, when Trump would sharply criticize the GOP elite for becoming entangled in foreign wars and argue that he could do better as a businessman and outsider who does not have an orthodox method.

“He used to say that everyone else who thought they could send representatives to cut big deals was stupid and that the protocols set up by those administrations seemed designed to fail,” former Trump aide Sam Nunberg said. “There was certainly an element of hubris to how he thought he could be the one who’d be able to solve things that others couldn’t solve.”

At a fundamental level, the GOP has also flailed in adjusting to Trump because most of its leading policy figures have had their ideas forged over decades through the prism of conservatism and a firm belief in a muscular foreign policy during the Cold War and through the administration of George W. Bush.

High-profile Republicans in Congress, such as the late senator John McCain of Arizona, have usually been hawkish defenders of alliances such as NATO.

While some veteran Republican hawks — such as Vice President Pence, Sen. Lindsey O. Graham (S.C.) and Senate Foreign Relations Committee Chairman James E. Risch (Idaho) — have become staunch Trump defenders, others have grown frustrated or resigned to Trump’s dominance.

“The Republican Party has been a free-trade party, a party of strategic alliances, and it’s been tough for a lot of Republicans to get used to this,” said Thomas H. Kean (R), a former governor of New Jersey and former chairman of the national 9/11 Commission. “Some have adjusted better than others, and the hawks have taken a step into the background.”

Since 2017, several Trump administration officials — including Rex Tillerson and Nikki Haley during their tenures as secretary of state and ambassador to the United Nations, respectively — have frequently appeared uneasy about, if not outright opposed to, aligning with Trump’s most incendiary statements about geopolitics.

Less than two months after joining the administration, Haley said she did not “trust Russia” despite Trump’s outreach to President Vladi­mir Putin. “We should never trust Russia,” she said.

Trump’s apparent reluctance to challenge Kim about the case of Otto Warmbier, the American college student detained in North Korea, caused a breach with Warmbier’s parents, who had previously praised Trump for calling attention to their son’s detention and successfully demanding his 2017 release. Warmbier died days after he returned to the United States with severe brain damage.

At a news conference following his meetings with Kim in Hanoi, Trump said he took the North Korean leader, who intelligence analysts say rules his country with an iron fist, at his word that he did not know what happened to Warmbier until after he fell into a coma.

“He felt badly about it,” Trump said.

In his interview with USA Today, Pompeo bristled when pressed about Trump’s comment — he said he had been “very patient” with the questions, according to the paper — before saying the North Korean regime was responsible for Warmbier’s death.

There are scattered Trump allies who share some of his instincts and aversion to foreign intervention, such as Sen. Rand Paul (R-Ky.), who has followed in the path of his father, Ron Paul, the retired Texas congressman and libertarian-leaning presidential candidate. On Tuesday, the younger Paul introduced legislation to stop “endless war” in Afghanistan and bring home U.S. troops.

At right-wing think tanks and in the community of Republican foreign policy specialists, hearty echoes of Trump are scarce.

“The White House has a really good messenger in Donald Trump but beyond that hasn’t developed a cadre of supporters” to rally behind him on foreign policy on television, said Trump friend and Newsmax chief executive Christopher Ruddy.

GOP anxiety over Trump’s behavior annoys hawkish Johns Hopkins University foreign policy scholar Eliot Cohen, an adviser to Condoleezza Rice during the George W. Bush administration and a fierce Trump critic.

“There is no excuse now for people to say ‘Oh, me, oh, my’ and ‘tut-tut’ and ‘I can’t believe that he would do that,’ ” said Cohen, who helped lead a revolt of seasoned Republican national security specialists in 2016. “His character was absolutely clear, and I don’t think you can work directly for this man and keep your character.”