In naming Patrick Shanahan as interim Defense secretary, President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE has elevated a former Boeing executive with less than two years of government experience to lead the Pentagon.

Trump on Sunday announced he would push out Defense Secretary James Mattis James Norman MattisBiden courts veterans amid fallout from Trump military controversies Trump says he wanted to take out Syria's Assad but Mattis opposed it Gary Cohn: 'I haven't made up my mind' on vote for president in November MORE two months earlier than the retired general’s planned departure, naming Shanahan as his temporary replacement.

Since his confirmation as deputy secretary in July 2017, Shanahan has ingratiated himself to the president by taking a lead role in Trump’s Space Force initiative and by implementing business reforms inside the Pentagon.

ADVERTISEMENT

And Shanahan has taken to his government role after spending a career in the corporate world.

“I tell people it's like breaking up with your longtime girlfriend and finding the love of your life,” Shanahan said at a conference in September.

Still, it’s unusual for the Pentagon to have an interim leader. After former Defense Secretary Chuck Hagel Charles (Chuck) Timothy HagelWhile our foes deploy hypersonic weapons, Washington debates about funding Hillicon Valley: Democrats request counterintelligence briefing | New pressure for election funding | Republicans urge retaliation against Chinese hackers National security leaders, advocacy groups urge Congress to send election funds to states MORE announced his resignation in December 2014, he stayed on until his successor, Ash Carter, was confirmed the following February.

Mattis said last week he would stay until the end of February to allow for a smooth transition. But Trump soon grew frustrated at the reaction to Mattis’s resignation letter — a sharp rebuke of Trump’s worldview — and decided Shanahan will be the acting secretary starting Jan. 1.

Shanahan’s name has also been floated as a possible long-term replacement for Mattis.

After Trump announced the personnel move in a tweet Sunday, Shanahan’s spokesman's, Lt. Col. Joe Buccino, only comment to the press was that "the deputy secretary of Defense will continue to serve as directed by the president."

ADVERTISEMENT

A son of a Vietnam veteran and a mechanical engineer with master’s degrees from MIT, Shanahan spent 30 years at Boeing before becoming the Pentagon’s No. 2 civilian in July 2017.

His career at Boeing included overseeing its rotorcraft program, which supplied the U.S. military with Apache and Chinook helicopters and helped build the V-22 Osprey tiltrotor.

In 2004, he took over Boeing’s missile defense program, helping develop the ground-based system.

He went on to oversee Boeing’s commercial airplane programs, where he become known as “Mr. Fix-it” for turning around the troubled 787 Dreamliner aircraft program. His last role before joining the Pentagon was senior vice president for supply chain and operations.

Shanahan’s financials disclosures when he was nominated by Trump last year showed he was invested in more than 400 diverse stocks for companies such as British American Tobacco, CBS, Diamond Offshore Drilling, Facebook, Marathon Petroleum and Qualcomm.

The disclosure forms, signed June 2017, listed his Boeing income as $1,419,864, as well as millions of dollars invested in the company.

In a letter accompanying the disclosures, Shanahan said he would divest all of his common stock and vested stock options in Boeing. He also divested in stocks in the defense industry, including firms like BAE Systems, CACI International, L3 Technologies and Orbital ATK.

He also pledged to "not participate personally and substantially" in matters involving Boeing if confirmed as deputy secretary.

However, Bloomberg reported this month that a Pentagon plan to request $1.2 billion for 12 Boeing F-15X fighter jets included some “prodding” from Shanahan.

The former Boeing exec had a somewhat rocky confirmation process to become deputy Defense secretary.

Trump announced Shanahan’s nomination in March 2017, but a confirmation hearing wasn’t held until June as Shanahan worked to untangle his financial ties.

At his confirmation hearing, Shanahan provoked the ire of late Senate Armed Services Committee Chairman John McCain John Sidney McCainThe Memo: Trump's strengths complicate election picture Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' Cindy McCain: Trump allegedly calling war dead 'losers' was 'pretty much' last straw before Biden endorsement MORE (R-Ariz.) for his defense industry background and his responses to questions about Russian aggression.

In written answers to the committee ahead of the hearing, Shanahan said he could not determine whether the United States should give weapons to Ukrainians fighting Russian-backed separatists until he had access to classified information.

An irked McCain asked him if he wanted to change his "not satisfactory" answer, to which Shanahan replied he would support providing the weapons.

“Not a good beginning. Not a good beginning. Do not do that again, Mr. Shanahan, or I will not take your name up for a vote before this committee,” McCain said.

As the hearing closed, McCain also gave Shanahan a warning that he was “not overjoyed” with the nominee’s extensive background working in the defense industry.

"I am concerned that 90 percent of defense spending is in the hands of the five corporations, of which you represent one," McCain told Shanahan. "I have to have confidence that the fox is not going to be put back into the hen house."

After Shanahan resubmitted his written answers on Russian aggression, the committee advanced him to the full Senate by voice vote. He was later confirmed 92-7.

At the Pentagon, Shanahan is not known to be close with Mattis and has focused on reforming the department’s business and administrative practices rather than getting involved with war fighting policy.

“Imagine if we drew a Venn diagram of Secretary Mattis and his skills and background and history and overlaid mine with it,” Shanahan told a defense industry group this year, according to Politico. “At the very edge they would touch, and it’s because we’re both from Washington state.”

In an October interview with Defense News, Shanahan said his job was to “operationalize” the National Defense Strategy, a document Mattis considers one of his biggest achievements as secretary.

Shanahan described his role as “driving systemic change — rewiring the organization to increase our performance on lethality, alliances and reform.”

The deputy secretary also became close with Trump and Vice President Pence as the Pentagon’s point-person for Trump’s Space Force plans. Shanahan has made frequent visits to the White House since this summer.

He has defended the plans for Space Force even as others in the Pentagon are skeptical of having a separate military branch for space. When the Air Force put the estimated cost at $13 billion, Shanahan insisted it would be much lower, possibly below $5 billion.

“We're really diligently putting together a proposal that can withstand the cost-scrutiny questions,” he said in November.

In a Dec. 9 op-ed for Defense News, Shanahan said the Pentagon’s focus in 2019 will be on missiles, space and cyber — three areas that he said “offer opportunities to assure our military advantage now and into the future.”

While Congress has been shaken by Mattis’s departure, Shanahan has already garnered some praise.

“President @realDonaldTrumps decision to elevate the Deputy Secretary of Defense Patrick Shanahan to Acting Secretary of Defense is a wise choice,” tweeted Sen. Lindsey Graham Lindsey Olin GrahamSenate GOP aims to confirm Trump court pick by Oct. 29: report The Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Senate GOP sees early Supreme Court vote as political booster shot MORE (R-S.C.), a Trump ally who has sparred with the president in recent days over his decision to withdraw from Syria and consideration of drawing down in Afghanistan.

Still, Shanahan will face questions from lawmakers who see Mattis’s exit as a bad omen.

“The unavoidable question for Patrick Shanahan is whether he has the conscience & courage to stand up for Mattis’ vital principles & policies,” tweeted Sen. Richard Blumenthal (D-Conn.). “If not, he’ll be complicit in Trump’s destructive course.”

Alex Gangitano contributed.