On Monday, in an account of the F.B.I.’s firing of Peter Strzok—the senior agent who led the Bureau’s 2016 investigations of Hillary Clinton e-mails and Trump-Russia connections—the Times reported that the move “was not unexpected.” Given the inflamed political climate in Washington, that is an accurate statement.

The special counsel, Robert Mueller, removed Strzok from the Russia investigation last year, after it was discovered that he had sharply criticized Donald Trump, who was then running for President, in private text messages with Lisa Page, another F.B.I. employee, with whom Strzok was having an affair. Earlier this summer, a report from the Justice Department’s inspector general, Michael Horowitz, said that Strzok’s text messages to Page “potentially indicated or created the appearance that investigative decisions were impacted by bias or improper considerations.” Since then, President Trump has been attacking Strzok regularly on Twitter. Last month, Strzok testified at a public hearing on Capitol Hill, where congressional Republicans tore into him. At one point, Rudy Giuliani, Trump’s lawyer, called for Strzok to be jailed.

But, despite all the noise and fury, there is now a basic question that needs an answer: Why was Strzok fired? Before the Clinton and Trump investigations, Strzok had racked up twenty years of distinguished service in the Bureau, rising to the position of deputy assistant director of the Counterintelligence Division.

Since his communications with Page have become public, Strzok has insisted that his personal views about Trump didn’t affect his actions while overseeing the Clinton and Russia investigations. During his testimony on Capitol Hill, he insisted that when, in the course of discussing Trump’s Presidential bid with Page, he wrote to her that “we will stop it” he was referring to the American public at large.

Some people, particularly Trump supporters, find that explanation hard to believe. So far, though, no convincing evidence has been unearthed that contradicts Strzok’s assertions. The inspector general’s report, which was confined to the Bureau’s handling of the Clinton investigation, stated, “Our review did not find documentary or testimonial evidence directly connecting the political views these employees expressed in their text messages and instant messages to the investigative decisions we reviewed.” Elsewhere, the report said, “We further found evidence that in some instances Strzok and Page advocated for more aggressive investigative measures than did others.”

The inspector general did express some concerns about the slow pace with which Strzok reacted, in September, 2016, to the discovery of thousands of Clinton’s e-mails on a laptop owned by Anthony Weiner, the estranged husband of Huma Abedin, a close aide to Clinton. By that point, Strzok was also overseeing the Trump-Russia investigation, which was expanding. In light of the contents of Strzok’s text messages, the inspector general’s report said, “We did not have confidence that Strzok’s decision to prioritize the Russia investigation over following up on the midyear-related investigative lead discovered on the Weiner laptop was free from bias.” But here, too, the report did not provide any actual evidence to support the theory that any of Strzok’s professional actions were politically motivated.

On Monday, Strzok’s lawyer, Aitan Goelman, claimed that his client’s firing had been ordered, late last week, by David Bowdich, the deputy director of the F.B.I., despite the fact that the Bureau’s Office of Professional Responsibility, which normally handles disciplinary matters, had recommended a lesser punishment: a demotion and a sixty-day suspension. “This decision should be deeply troubling to all Americans,” Goelman told the Times. “A lengthy investigation and multiple rounds of congressional testimony failed to produce a shred of evidence that Special Agent Strzok’s personal views ever affected his work.”

As of late Monday afternoon, there was still no official word from Bowdich or his boss, Christopher Wray, about Strzok’s dismissal. The Times and the Wall Street Journal both reported that a spokesperson for the F.B.I. didn’t respond to requests for comments about Strzok’s firing.

It is perhaps possible that Bowditch and Wray have some damaging information about Strzok that we don’t know about. Horowitz, the inspector general, is still carrying out a separate inquiry into the Bureau’s handling of the Trump-Russia investigation. Conceivably, he could have found something damning and tipped off Bowditch and Wray.

If there is such information, the F.B.I. needs to make this clear immediately. At the very least, it needs to explain the basis of the decision to dismiss Strzok, pointing out which internal rules he violated, and why these violations amounted to a firing offense. As things stand, it looks like the Bureau’s leaders buckled to Trump and his political and media outriders, dispensing with departmental norms and setting a highly disturbing precedent.

In a tweet that he posted just after noon on Monday, Trump crowed about what had happened. “Agent Peter Strzok was just fired from the FBI - finally,” he wrote. “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!”

In his larger quest to end the Mueller investigation, Trump clearly sees Strzok’s dismissal as a victory, albeit a relatively small one. That should be sufficient cause for alarm. Encouraged by what happened here, Trump will surely expand his attacks on Mueller and his colleagues. The leaders of the F.B.I. need to start talking.