If there’s one thing for which it’s impossible to fault Donald Trump, it is the clarity of his intentions.

As he has emphasized in scores of tweets and public statements, he believes that the investigation into his campaign’s ties to Russia is illegitimate and that the president should have much greater sway over the decisions of the country’s law enforcement agencies.

This conviction is the reason why he keeps attacking Robert Mueller. It is the reason why he and his allies have orchestrated a ferocious campaign to undermine the senior leadership of the FBI and the Department of Justice—from Andrew McCabe, who was fired in March, to Rod Rosenstein, who is still holding onto his job by a thin thread. And it is, as Trump himself admitted Monday, also why he has long called for the head of Peter Strzok, the senior FBI agent who sent private text messages that were highly critical of Trump and who was unceremoniously fired Monday.

Agent Peter Strzok was just fired from the FBI - finally. The list of bad players in the FBI & DOJ gets longer & longer. Based on the fact that Strzok was in charge of the Witch Hunt, will it be dropped? It is a total Hoax. No Collusion, No Obstruction - I just fight back! — Donald J. Trump (@realDonaldTrump) August 13, 2018

In the wake of this news, talking heads and opinion writers are battling about whether Strzok did anything sufficiently egregious to justify his firing. It is true that there is considerable evidence that he at times fell short of the FBI’s exacting professional standards. As a report by the bureau’s inspector general pointed out, he may have been at fault in not moving fast enough to investigate an additional trove of Hillary Clinton’s emails recovered from Anthony Weiner’s laptop. He violated standard security policies by forwarding the draft of a search warrant affidavit containing highly sensitive information to his private email address. And while employees of the FBI are of course at liberty to express their personal political views in private conversations, the careless phrasing of some of his text messages—asked whether Trump could ever become president, he responded: “No. No he won’t. We’ll stop it.”—could reasonably undermine public confidence about the independence of the bureau.

However, there is also strong evidence that Strzok’s personal views did not affect his professional conduct and even more compelling evidence that they did not sway the actions of the bureau as a whole. And while some of Strzok’s text messages do sound damning when taken out of context, the overall exchange makes it amply evident that he was not proposing some deep state plot to undermine Trump’s candidacy. As the inspector general’s report concluded, “we did not find documentary or testimonial evidence that improper considerations, including political bias, directly affected the specific investigative decisions we reviewed.”

But the minutiae of Strzok’s conduct are ultimately a distraction. The most important question right now is not “Were Strzok’s failings sufficiently grievous for him to get fired?” It is, rather: “Did he get fired because of his failings—or did the FBI buckle under the enormous pressure exerted by Donald Trump?”

That question is, unfortunately, far easier to answer. Testifying in front of Congress in June, the director of the FBI, Christopher Wray, promised that the investigation into Strzok would be “done by the book.” But that is emphatically not what happened. The bureau’s Office of Professional Responsibility merely recommended that Strzok be demoted and suspended for 60 days. But it was then overruled by David Bowdich, the deputy director of the FBI As Bradley Moss, a leading national security lawyer, has pointed out, that step was “highly unusual. Maybe legal but definitely not standard practice.”

This should make us very concerned about the impending clash between Trump and his real target: Robert Mueller.

And this is why the crux of this complicated saga is actually pretty straightforward. Strzok stood accused of undermining public trust in the independence of the FBI through his carelessness. This is indeed a significant offense, one that liberals and conservatives alike should take very seriously. But by caving to a massive campaign of vilification by the president, and publicly violating Wray’s promise that the investigation into Strzok would be done by the book, the bureau’s leadership has undermined that trust in a much more public, deliberate, and grievous manner than the man they scapegoated ever did.

Even at this late stage, many commentators still take it for granted that Trump’s attempts to curb the independence of key political institutions will miraculously be foiled by the Constitution. But Strzok’s firing is only the latest in a series of cases in which high-ranking civil servants have been personally attacked by the president and then been forced to leave office under highly unusual circumstances: At this point, Trump has managed to dispatch the FBI’s director, its deputy director, its general counsel, and the head agent of its investigating agency.

This is worrying for two important reasons. First, it sends a clear message to rank-and-file bureaucrats across different agencies: If you value your career, you better stay in the president’s good books. It will take years or decades until we gain the full measure to which this message may already be swaying supposedly apolitical decisions at all levels of the government. And if the message keeps being sent in ever more high-profile cases, we will have to start worrying that political pressure could influence the behavior of key institutions in ways that are directly inimical to the proper functioning of a democracy (like, for example, an investigation of the 2020 Democratic presidential candidate on trumped-up charges).

Second, it should make us very concerned about the impending clash between Trump and his real target: Robert Mueller. As Rep. Devin Nunes recently reminded us in his shocking remarks at a private fundraiser, many Republican legislators are now determined to defend the president against any meaningful investigation at just about any cost. The received wisdom remains that Trump cannot possibly win such an open confrontation. If Trump removes Mueller, the smart money says, it would mark the effective end of his presidency. But so far, Trump has amassed a strikingly strong batting average when it came to getting the targets of his ire fired from their jobs.

So if the strange saga of Peter Strzok does nothing else, it should refocus our attention on the urgency of defending the independence of our key political institutions, including the FBI and the Mueller probe.

As the experience of countless other countries, from Russia to Turkey, shows, attacks on the rule of law often start with the politically motivated purge of comparatively minor figures whose record is not entirely clean. Once institutions that are supposed to be independent from the head of state become accustomed to yielding to political pressure, the demands keep ratcheting up. Before long, any critics of the government know that they are unlikely to receive the same treatment as other citizens.

We are still far from that dystopia. But despite Strzok’s undoubted failings, the highly irregular manner of his firing is another early link along the chain that leads from the rule of law to what the Founding Fathers rightly deplored as “the rule of men.”