In a six-day trip that took him to four cities on two continents, acting defense secretary Patrick Shanahan came face to face with one consistent reality last week: the discord generated by President Trump and his “America First” agenda.

For the first time since becoming Pentagon chief last month, Shanahan was asked to answer for the uncertainties produced by the president’s often unpopular foreign policy.

The former Boeing executive, who took over in January after the abrupt resignation of his predecessor, Jim Mattis, deferred to the president’s decisions and suggested, in high-level talks, steps that U.S. allies can take to adjust.

At the conclusion of the trip, Shanahan told reporters that he had anticipated a “more standoffish” reception.

“The pushback was we need these issues addressed, these questions answered,” he said. “There were no promises or guarantees, but there was support.”

As Shanahan publicly auditions to keep the military’s top job, the gaps that critics have identified in his résumé could win him favor with his commander in chief: slim foreign policy experience and limited investment in the counterterrorism wars that have monopolized the military’s focus for two decades.

“Shanahan comes from the business executive world, and he’s considerably freer about some of the guardrails of the Washington foreign policy establishment,” said Elbridge Colby, a former Pentagon official who worked closely with Shanahan. “He’s not afraid to leave some things in the past.”

Current and former officials described a more dispassionate approach to the counterinsurgency campaigns that have emerged as a friction point between Trump and his generals.

Since becoming the Pentagon’s No. 2 in 2017, Shanahan has brought a private-sector view to his priorities of modernizing the military and preparing for possible conflict with China. Like the president, he has little previous experience with the wars in Iraq and Afghanistan.

The officials, who spoke on the condition of anonymity to speak candidly, said Shanahan takes a results-oriented view of those conflicts, which have failed to produce lasting security despite almost two decades and billions of dollars of effort.

Colby said there was “a lot of water under the bridge” for senior military leaders, in contrast, when it comes to those wars. “If you’re going to lead people into the fight in Iraq or Afghanistan, you have to believe in it,” he said. “They’ve been to Arlington too many times to fake it.”

The 56-year-old engineer takes over at the Pentagon at a moment of intensified congressional oversight and controversy over the president’s moves to involve the military in his plans for the U.S.-Mexico border.

When Mattis quit in December over differences with Trump, Shanahan was a little-known quantity outside the Pentagon. Mattis, a retired Marine general, cut a larger-than-life figure in Washington, lauded by members of both parties for seeking to steer Trump toward traditional foreign policy positions. Shanahan was more focused on internal Pentagon matters. While he sometimes attended top-level White House meetings on Mattis’s behalf, his chief responsibilities were less visible, including a Pentagon audit and a proposal to create a new space force.

Shanahan, known during his decades-long Boeing career as a driven manager who helped turn around the company’s troubled Dreamliner program, brought an unceremonious, West Coast style to the Pentagon, former colleagues said. For weekend work sessions, he would show up in workout gear and jeans, and occasionally ribbed other officials who came in button-downs and khakis.

While how much progress Shanahan made in reforming the department’s byzantine practices remains a matter of debate, he seemed to connect with Trump, another businessman and Washington outsider.

“The challenge for him will be the need to move from deputy, focused on internal matters, running the Pentagon, budgetary matters, business processes and so on, to a highly visible, foreign policy-inflected role in a highly unusual administration,” said Richard Fontaine, president of the Center for a New American Security and a former adviser to the late senator John McCain (R-Ariz.).

As acting secretary, Shanahan is responsible for ushering core defense alliances through a period of unprecedented tension over Trump’s decisions on Syria, Afghanistan and arms control, and his adversarial approach to trade, Iran and multilateral organizations.

In Afghanistan last week, Shanahan met with President Ashraf Ghani, who has voiced concern that the Trump administration could give too much away in nascent peace talks. Afghan leaders were unnerved late last year when military officials were instructed to begin drawing up plans for a major troop reduction at a time when Taliban militants continued to pose a major challenge.

In Iraq, he held talks with Prime Minister Adel Abdul Mahdi in the wake of political uproar caused by Trump’s suggestion that the United States could leave troops in the country to “watch Iran.” That statement energized Iraqi lawmakers who support legislation that could scuttle plans for a continued U.S. counterterrorism mission there.

The friction was most evident in Europe, where Shanahan met with NATO ministers in Brussels and attended a global security conference in Munich. There, German Chancellor Angela Merkel received a standing ovation when she pushed back against Trump administration decisions Europeans see as unilateral and unjustified. Many European countries have complained that the decisions to remove troops from Syria and possibly Afghanistan were made without consulting allies fighting there too and could allow militants to regroup.

Analysts said NATO leaders were anxious to take stock of the person replacing Mattis, who won European support as he appeared to exert unparalleled influence over Trump, securing a troop increase for Afghanistan and backing for traditional alliances.

Ivo Daalder, president of the Chicago Council on Global Affairs and a former U.S. ambassador to NATO, said those leaders will evaluate Shanahan through the lens of Mattis’s ultimate failure to convince Trump of the merits of more traditional foreign policy views. During Mattis’s tenure, Trump pushed through a series of moves opposed by many Pentagon officials, including a costly military parade and suspension of military exercises with South Korea.

“It was clear that Trump was his own boss by 2018,” Daalder said. In that light, he said, “frankly, there isn’t anything [Shanahan] can do or say to reassure allies in the way that Mattis could. That’s his unenviable position.”

Continued uncertainty about Shanahan’s own future could also diminish his effectiveness with already skeptical allies. Trump has said he prefers having Cabinet members who have not been confirmed, saying that keeping subordinates in an acting capacity increases his flexibility and allows him to “go fast.” While Trump has publicly praised Shanahan, it remains unclear where Shanahan’s views may differ from the president’s and how much he will challenge him when they do.

Shanahan’s advisers judged his inaugural trip a solid performance. It will now be up to Trump whether he nominates Shanahan, leaves him in the job in an acting status, or chooses someone else.

As he sought to make a favorable first impression, and with a president with often inscrutable personnel preferences, some of the biggest buzz of Shanahan’s tour was related to his sartorial choice. Stepping out of a helicopter when he touched down at a military base in Kabul, Shanahan’s angular dark jacket and black turtleneck contrasted with the Pentagon’s unofficial civilian uniform of oxford shirt and blue blazer.

The acting secretary made light of the moment days later. “Did you like my outfit?” Shanahan asked British Defense Secretary Gavin Williamson as the two men shook hands at NATO headquarters.

“I did, I did,” Williamson replied. The consensus, he said: “You look like Special Forces.”