In NSC staff meetings, the impeachment inquiry is “the elephant in the room and no one talks about it,” said a serving council official, adding: “When you’re not transparent about what’s going on, this is how rumors get started.”

The NSC consists largely of career government staffers detailed from other departments and agencies, such as the Pentagon and the CIA. Under the direction of the national security adviser, they work with Trump’s political appointees in directorates that cover specific regions of the world or issues such as counterterrorism.

The impeachment inquiry coincided with Trump’s selection of Robert C. O’Brien as the new national security adviser to replace the ousted John Bolton. While many at the NSC were happy to see Bolton gone — he was viewed as too aloof and too unwilling to use the traditional NSC decision-making process — it means enduring a third leadership change in less than three years.

Political appointees are wondering whether O’Brien will keep them. Career staffers are wondering what issues he will prioritize. And there are across-the-board worries that the fallout from the impeachment process could lead to even stricter information controls inside the NSC, making it harder for people to access what they need and to collaborate.

“There’s a general concern, or even maybe more than just concern, that we’re going to reach a state of paralysis now on national security issues and policy issues,” said a former NSC official in touch with several people across the organization. “The people I’ve talked to are interpreting the coming weeks and months as generally not productive.”

The people most worried are those who deal with Ukraine and Europe more broadly, said another former NSC official. That’s because at the heart of the impeachment crisis is a July 25 phone call between Trump and his Ukrainian counterpart, Volodymyr Zelensky.

According to a detailed call memo released by the White House, Trump pressed the Ukrainian president to investigate alleged shady actions by former Vice President Joe Biden and his son Hunter. There’s no evidence the Bidens did anything wrong. But Joe Biden is seeking the Democratic presidential nomination, so Trump stands accused of pressuring a foreign government to investigate a potential political rival.

A whistleblower’s complaint fueling the impeachment inquiry says administration officials, under the direction of White House lawyers, took the written record of that conversation out of the system where it would usually be stored and put it in a more secure system, possibly to cover up the president’s actions.

It’s not yet clear how many people in the NSC played a role in deciding where to place the call record, or otherwise engaged in questionable Ukraine-related activities linked to the impeachment inquiry, but the investigation is damaging to morale, especially for those in the relevant directorates.

“The people in the Ukraine section are feeling really down,” a second former NSC official said, adding that it’s especially true for the career staffers. “Their type of work in the background, behind the scenes, is being exposed to the world. Their professionalism is getting politicized.”

Texts released this week as part of the inquiry mentioned at least one NSC staffer, senior director Tim Morrison, though his exact knowledge of the events is unclear. The texts suggest Morrison was involved in trying to set up a phone call between Trump and Zelensky and looking at ways to arrange a Zelensky visit to the White House. He did not respond to a request for comment.

John Gans, author of “White House Warriors,” a book about the NSC, said that, like the Iran-Contra scandal, the Ukraine-related impeachment inquiry has the potential to “rip open the sausage of national security policymaking,” and that the impact on the institution and its people could be serious.

NSC officials, such as Oliver North, were implicated in the convoluted Iran-Contra affair. In that controversy, the administration of President Ronald Reagan secretly sold weapons to Iran, then funneled the money to rebels battling a communist-influenced regime in Nicaragua. The scheme appeared designed to bypass U.S. law. Reagan also hoped that it could help free U.S. hostages being held in Lebanon by Hezbollah, an Iran-backed group.

The affair’s exposure badly stained the NSC’s reputation and spawned several investigations. One panel investigating, known as the Tower Commission, called for limited structural changes to the NSC. Most consequentially, it recommended that the national security adviser and his staff avoid running operations and stick to advisory and coordination work.

Gans noted that over the past two weeks, there have been indications that the president may have asked governments beyond Ukraine’s to investigate the Bidens or otherwise act in ways that benefit him personally. On Thursday, for instance, Trump publicly called on China to look into the Bidens, leading to even more hand-wringing in Washington.

Depending on how far Democrats want to take their inquiry, it could drag in other pieces of the NSC, not to mention the State Department and other agencies making national security policy. Based on what happened under Iran-Contra, Gans recommended that NSC staffers who have any ties to the Ukraine controversy, at least, get lawyers.

“On Iran-Contra it became every man for themselves,” Gans said, predicting that under Trump: “It will be very dark. And I think anarchic. Your career prospects might be dimmed. This was supposed to be the highlight of your career and now it’s going to be a lowlight.”

The first former NSC official said one concern he’s hearing from people inside the organization is that it will become even harder to recruit people to fill positions. Most such roles are usually filled by detailees from other parts of the government.

Under the Obama administration, there was intense competition for NSC slots given their prestige. Over the past three years, however, that interest has fallen dramatically, said the former NSC official, who’s seen the application numbers but declined to specify them.

With the impeachment inquiry looming, interest could dwindle even further. “I feel like you already don’t have an A Team or B Team. You’re really getting down to who’s left that will say ‘yes,’” the former official said.

Trump administration spokespeople downplayed such concerns.

"The National Security Council staff is comprised of exceptional public servants from across the U.S. Government who are working diligently to support President Trump's highly-effective national security agenda. There is no shortage of patriotic individuals willing to work on these critical issues," White House press secretary Stephanie Grisham said in a statement.

NSC spokesman Mike Martin noted that "NSC positions are among the most coveted in the U.S. government” and said people there now are “hard at work, as they should be and will continue to be.”

O’Brien’s arrival has so far been fairly smooth, current and former officials say, although he spent most of his initial days in New York at the U.N. General Assembly. This was his first full week in Washington, and staffers are hoping he will give each directorate some face-time.

NSC staffers are widely pleased with O’Brien’s choice for his deputy, Matt Pottinger. Pottinger, a former Wall Street Journal reporter and military veteran, has been serving as a senior Asia hand on the council. He’s considered highly competent and organized.

“Generally speaking, people love Matt Pottinger,” the current NSC staffer said. “The best thing they could have done was to keep him and elevate him.”

O’Brien is expected to bring over some of his aides from the State Department, where he had been serving as a special envoy dealing with hostage issues. NSC staffers also have been told O’Brien will press forth with a process, initiated under the Obama administration and kept up under Trump, to shrink the overall size of the organization. Bloomberg first reported the plans for the cuts, which will be handled largely through attrition.

The organization’s exact size and structure are not made public, but it’s been reported to have risen above 300 people under Obama. Exactly whom, if anyone, O’Brien asks to leave will be watched carefully in case there are any connections to the Ukraine-related crisis.

“One question people are asking,” the current NSC staffer said, “is ‘Are the implicated NSC people going to stay or kicked out’? I’m surprised these people are still here.”

A former administration official who knows several political appointees at the NSC said many of them feel protective of the president, “almost, like, defiant.” But given how busy they are, most are too focused on their work to dwell on the impeachment inquiry.

The former administration official also downplayed comparisons to Iran-Contra, saying it’s highly unlikely NSC staffers themselves did anything wrong. If there was any inappropriate action, it originated in the Oval Office, the State Department, or elsewhere outside the NSC’s boundaries, the former official said.

Gans, however, pointed out that in Washington, scandals often consume the unsuspecting.

“I assume 99 percent of people are innocent,” Gans said. “But that doesn’t mean they’re not going to have to pay for lawyers or not worry about the future of their careers."