When President Trump revoked former CIA director John Brennan’s security clearance last week, many considered the act to be retaliation against an outspoken critic of the administration. Trump’s move — which he linked to his frustration with the Russia investigation — may have broader implications for the intelligence-policy relationship for years to come, however.

Tensions within the national security community escalated quickly. In an Aug. 16 op-ed, retired Adm. William H. McRaven, a former commander of the U.S. Joint Special Operations Command who oversaw the Osama bin Laden raid in 2011, asked Trump to revoke his clearance in solidarity.

That evening, 12 of the nation’s most senior retired intelligence officials from both parties signed an open letter condemning Trump’s decision to revoke Brennan’s clearance. And more former intel officials have signed on or written additional letters since.

Trump is purportedly considering revoking the security clearances of other retired officials, all of whom have been openly critical of his administration. Whether such actions fall within the purview of his Article II powers as commander in chief or constitute a violation of the First Amendment is an important legal question and one the courts may take up in the coming months.

But what’s the bigger impact on U.S. security? Here’s what you need to know.

Intelligence-policy relations seldom run smoothly

It is important to note that Trump’s combative attitude toward intelligence is somewhat familiar. Other U.S. presidents have harbored reservations about the intel community and its top officials. Richard Nixon famously believed that the CIA conspired to thwart his bid for the presidency in 1960.

During his 1976 presidential campaign, Jimmy Carter regularly attacked the CIA for past actions, vowing to put the United States on a more ethical footing. Bill Clinton kept CIA Director James Woolsey at arm’s length, reflecting his own ambivalence toward intelligence.

But the frequency and ferocity of Trump’s attacks are unlike anything we’ve seen. Days before his inauguration, Trump openly compared the U.S. intel community to Nazi Germany. During the July summit in Helsinki, Trump seemingly sided with Russian President Vladimir Putin, dismissing the consensus of U.S. intelligence officials that Russia interfered in the 2016 presidential election.

And the politically motivated decision to revoke Brennan’s security clearance — in the absence of any evidence of misuse of classified information — is also unprecedented. Senior officials often keep their clearances so they can advise their successors after they leave government. Trump doesn’t seem concerned about losing this expertise. One presidential historian likened his moves to the tactics used by Nixon and Joseph McCarthy to harass political opponents.

Trump’s move could make neglect and politicization more likely

Although it’s too soon to tell how all of this will play out, research on the dynamics between policymakers and intelligence paints a relatively bleak picture. Security scholar Joshua Rovner identifies several pathologies of intelligence-policy relations in his book “Fixing the Facts.” At least two of them — neglect and politicization — are potential consequences of Trump’s recent actions.

In an ideal world, intelligence analysts provide objective assessments to senior officials that help them make more informed foreign policy decisions. This relationship breaks down when policymakers selectively focus only on favorable assessments and willfully ignore the rest, otherwise known as neglect. This can happen for several reasons, including excessive confidence in their abilities and the tendency to lean too heavily on personal interactions as guides to policy.

Trump seemed to enjoy a close relationship with Mike Pompeo, whom he tapped to head the CIA in January 2017. But numerous accounts suggest that the president sees the U.S. intelligence community as part of a “deep state” that looks to undermine him at every turn. To the extent that the open letter condemning the decision to revoke Brennan’s security clearance solidifies these views, it is plausible that Trump could turn even further away from the intel community.

And there’s a second possible consequence of this week’s clearance saga: politicization, or “fabricat[ing] or distort[ing] information to serve policy preferences or vested interests.” This could involve direct politicization — when policymakers actively intervene to alter analytic conclusions produced by the intelligence community.

Indirect politicization is more subtle. It occurs when “intelligence tells policy what it wants to hear without having to be asked.” According to Rovner, politicization is “most likely when the political stakes are very high, and when leaders make public statements on controversial issues that are out of step with intelligence judgments.”

Trump’s threat to revoke the clearances of other former officials could increase the pressure on current intel officials to toe the line — or face reprisals. Tacit signals from the White House about what will or won’t be viewed favorably could generate incentives to produce estimates that support stated policy regardless of the facts.

Moreover, the backlash against Trump’s decision from career officials may result in “manipulation by appointment,” wherein partisans and other loyalists are elevated to positions of power within the intelligence community under the presumption that they will be loyal and provide rosy assessments.

The downstream effects could be far-reaching

If Trump’s moves do indeed result in wholesale neglect or politicization, this could prove very risky. Here’s an example: If dissenting voices in the intel community are suppressed because of this type of politicization, the United States may be more likely to stumble into a potentially catastrophic secret intervention, whether in Iran or elsewhere. And pursuing covert operations without the cooperation of the intelligence community could result in domestic legal troubles down the road. Ronald Reagan learned this lesson the hard way during the Iran-contra affair.

The latest squabble between Trump and the intelligence community also may end up damaging the reputation of U.S. intelligence officials in the long run. Those who wade into the policy arena run the risk of undermining their perceived objectivity. (McRaven’s decision to lend his voice to the fray raises similar concerns from the vantage point of civil-military relations.)

This is why some scholars think it’s best for these officials to “err on the side of silence.” If the public backlash against Trump is viewed as just another partisan attack against the president — despite the fact that many of the recent critics have served Republican presidents or are themselves Republicans  — the intelligence community’s role and image as a neutral arbiter of truth may suffer.

Editor’s note: This post was updated to clarify President Trump’s relationship with Secretary of State Mike Pompeo.

Michael Poznansky (@m_poznansky) is an assistant professor of international affairs and intelligence studies in the Graduate School of Public and International Affairs at the University of Pittsburgh.