National security adviser John Bolton's top deputy is described by some as a no-nonsense, tough-as-nails government official who doesn't suffer fools gladly.

But she has also rankled some administration officials since coming onboard earlier this year.

Mira Ricardel, who garnered attention recently for butting heads with 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, is a defense hawk in line with Bolton and a veteran of three administrations.

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Beyond the Beltway, the 58-year-old is largely unknown. In Washington, her influence, expertise and strong personality are defining traits to those who have worked with her in various roles.

“She does not suffer fools well,” said Steven Bucci, who worked with Ricardel at the Pentagon in the early 2000s while he was the military assistant to then-Defense Secretary Donald Rumsfeld.

“She’s pretty impatient with people who are unprepared or try to get into an intellectual knife fight with nothing in their hands," he added. “She’s definitely not intimidated by anybody."

Now, the former Boeing executive is in the White House, and her star is rising at a time when the futures of some of her administration counterparts are in question.

Though she’s kept a low public profile since Bolton brought her on in April — one of his first senior-level hires after becoming head of the National Security Council (NSC) — Ricardel found herself in the news recently when The New York Times reported that a tussle between her and Mattis over Pentagon appointments early in the Trump administration led to smoldering tensions ever since.

Ricardel, who prior to the 2016 election was named head of Pentagon appointments on Trump’s transition team, reportedly stopped Mattis from hiring certain officials over concerns about their party affiliation or their earlier support for Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE.

One defense expert who worked with Ricardel on the transition team said the disagreement with the Defense secretary stemmed from Mattis's goal of hiring nonpartisan officials, while the White House sought Republican loyalists.

“Mattis didn’t want people that are overtly political ... and I think Mira’s instincts were more toward, ‘Look, it’s the administration’s team, the administration’s people ought to be there,’” the expert said. “I don’t think either one of them hold grudges or keep scores about that.”

The dispute was over two potential hires who had worked under Democratic presidents: Michèle Flournoy, a Pentagon official under former Presidents Obama and Bill Clinton William (Bill) Jefferson ClintonChelsea Clinton: Trump isn't building public confidence in a vaccine Hillary Clinton launching podcast this month GOP brushes back charges of hypocrisy in Supreme Court fight MORE, and Anne Patterson, a career diplomat who served under Obama, Clinton and former President George W. Bush.

Some say the long-term effects of any such disagreement between the two officials have been exaggerated.

Bucci, who is now with the conservative Heritage Foundation, said the story has been “a little overblown.”

“When Mattis came in he changed the plans that Mira, as the head of the transition team, had already begun,” Bucci said. “They weren’t radically different. If Mira picked 10 people to come in on the transition team, Secretary Mattis said, ‘OK, let’s do these five, but I’ve got five other people that I want to bring in instead.’”

Bucci described the Ricardel-Mattis relationship as professional and noted that such conflict is “kind of how governments work.”

“I think there are probably some differences on specific policies,” he added. “They are all going to have slightly different positions because of where they sit. That doesn’t mean that there’s rampant conflict between them.”

One administration official described the situation this way: “It’s not a secret that when [Ricardel] was the head of personnel there was some disagreement about who should come in. I don’t think it was as bad as has been reported, but there was definitely a difference of opinion.”

Media reports at the time of the transition also suggested Ricardel herself wanted a top job at the Pentagon but was blocked by Mattis.

A senior administration official pushed back on that account.

“Mira was designated to do transition staffing for the Department of Defense during the transition,” the official told The Hill. “Her job was to identify candidates to fulfill the president’s agenda, which she did.”

“The narrative that she wanted the job and didn’t get it is just not accurate,” the official added.

In a statement to The Hill, the Pentagon indicated there was no ill will between Mattis and Bolton’s NSC staff.

"Secretary Mattis has a good working relationship with Ambassador Bolton and his team," chief Pentagon spokeswoman Dana White said.

Ricardel offered a similar assessment.

“The NSC is coordinating across government agencies to implement the President’s agenda, including with the Defense Department under the leadership of General Mattis, for whom I have great respect,” she said.

But that level of coordination has led to consternation among some in the administration.

At the NSC, one of Ricardel’s primary duties is interagency policy coordination between the NSC and places like the State Department, Pentagon and Commerce Department.

"There are people across the interagency with varying degrees of frustration about the current coordination process, given some of the outstanding issues that require NSC leadership," the administration official told The Hill.

One of those concerns involves getting the NSC and Defense Department on the same page when it comes to major policy issues like the administration’s cyber strategy, the military’s role in Syria and responding to Iranian aggression, according to some officials.

“Given some of the issues that have lingered — cyber, Syria, Iran — big issues out there that require NSC leadership to coordinate, they’re still kind of out there,” the administration official said.

The apparent disconnect was on display when Bolton said in a speech last week that the United States will keep troops in Syria until Iran withdraws its forces from the war-torn country.

Shortly after Bolton’s remarks, Mattis told reporters at the Pentagon that there was no change in policy and that the 2,200 U.S. troops inside Syria “are there for one purpose, and that’s under the U.N. authorization about defeating ISIS.”

Mattis insisted that he and Bolton were “on the same sheet of music.”

Complicating matters is the fact that principal meetings between the NSC and top national security officials that are meant to ensure consensus on major policies have decreased in frequency under Bolton.

But that’s not a bad thing, according to Russell Vought, who described Ricardel as “tough and very knowledgeable.”

The deputy director of the Office of Management and Budget told The Hill that while there have been “slightly” fewer meetings under Bolton, the new format has been helpful.

“It gives us the opportunity to really be intentional and use the time that we have,” he said. “It’s not because work is not being done on that process. It means, from my perspective, we’re able to focus on the big-ticket items and to really have a good discussion and make sure agencies aren’t coming in too many times to the White House.”

Ricardel has received high praise from other top officials, including a Cabinet member, who say her NSC position plays to her strengths.

“There’s nobody I have more respect or admiration for than Mira,” said Veterans Affairs Secretary Robert Wilkie, who worked with Ricardel in the mid-1990s when she was a legislative assistant in the office of then-Senate Majority Leader Bob Dole (R-Kan.).

Wilkie at the time was a staffer for then-Sen. Trent Lott (R-Miss.), who succeeded Dole as majority leader.

“As senator staffers, we were pretty much what you’d call singletons,” Wilkie said. “We were staffs unto ourselves. I was always impressed by her knowledge of my area, foreign policy and defense.”

That characterization was a common theme among her former colleagues.

Former Deputy Defense Secretary Paul Wolfowitz called her “tough in a very effective way.”

“She had an excellent reputation, except with people who lost to her, because she won a lot of battles, which I admire," said Wolfowitz, who was an informal adviser to former Dole when Ricardel worked for the senator.

Arnold Punaro, a former staff director for the Senate Armed Services Committee who has known and frequently worked with Ricardel over the course of nearly 30 years, said her personality traits make her a good fit for the role she’s in.

“She’s a forceful individual, but that’s what you need when you’re running the deputy’s committee because you’re corralling a lot of disparate, high-level viewpoints,” Punaro said. “She is not a shrinking violet by any stretch of the imagination. But, frankly, in the times we’re in, you want somebody like that.”