Michael Cohen’s decision to plead guilty to lying to Congress on Thursday was remarkable for three reasons.

The first was that Cohen walked into a Manhattan federal courtroom unannounced. He did it by surprise. We live in a political environment characterized by constant leaks, each choreographed more carefully than a public announcement. The drama of learning what’s going to happen at an event, rather than before the event, has mostly disappeared. But Cohen’s plea, a momentous development in Special Counsel Robert Mueller’s investigation, happened with no warning. That reflects admirable discipline in Mueller’s office.

The second remarkable thing was that the plea happened at all. Cohen already pleaded guilty in August to eight federal felonies, including tax fraud, bank fraud, and campaign-finance violations. That plea already ended his career and exposed him to at least several years in federal prison. By contrast, Cohen’s new plea is to a lone count of lying to Congress in violation of Title 18, United States Code, Section 1001 —a weapon Mueller has wielded ruthlessly against President Donald Trump’s followers, including Michael Flynn, George Papadopoulos, Rick Gates, and Paul Manafort. The conviction won’t increase Cohen’s sentence, and the additional felony count won’t have any perceptible impact on his life. If anything, by adding a cooperation term to his plea agreement, this new plea gives him an opportunity to reduce his sentence.

Read: What Michael Cohen’s guilty plea means for Trump

Normally, federal prosecutors don’t waste time with this sort of rubble-bouncing. So why would Mueller spend the time and resources on it? Because it tells a story about Trump and his campaign. Because it lays a marker.

It’s not clear whether the Constitution allows Mueller to indict a sitting president. But Department of Justice policy forbids it, and Mueller is a rule-follower. If Mueller thinks that the president has committed a federal crime, his remedy is to recommend impeachment in a report to the attorney general. The attorney general, in turn, is supposed to tell Congress the outcome of the special counsel’s investigation and decide whether the report should be made public. Did you catch the problem? The acting attorney general is Matthew Whitaker, Trump’s creature and a vigorous critic of Mueller’s investigation. Mueller has every reason to expect that Whitaker will suppress the report and limit what he shows to Congress.

A formal report is not, however, Mueller’s only way to tell Congress—and the nation—about his conclusions. The journalist Marcy Wheeler has written extensively about her theory that Mueller will “make his report” through court filings against Trump confederates like Manafort and Cohen. On Monday, Mueller accused Manafort of lying to investigators, breaching his cooperation agreement, and committing further federal crimes; he promised he’d bring the receipts when he filed briefs urging a long sentence. Those sentencing briefs will let Mueller tell the story of how Manafort lied about the Trump campaign—and, by extension, lay out the evidence of what the Trump campaign did.

Peter Beinart: We’re all Michael Cohen

Cohen’s case lets Mueller do the same thing—tell a story, make a report. The information—the charging document to which Cohen pleaded, waiving his right to indictment by grand jury—asserts that the Trump Organization planned a hotel in Russia, communicated with Russian officials about it, and even contemplated sending Trump himself for a visit to Russia well into 2016, contrary to Cohen’s congressional testimony that the plan was abandoned in January 2016. The significance is not just that Cohen lied to Congress. The significance is what he lied about: the fact that Team Trump continued to pursue Russian opportunities well into the campaign. Not only that, but the Information also asserts that Cohen kept Trump (whose identity is not at all concealed as “Individual 1”) and others within the campaign informed about his progress in Russia.

The third remarkable thing about Cohen’s plea was its substance. The president of the United States’ personal lawyer admitted to lying to Congress about the president’s business activities with a hostile foreign power, in order to support the president’s story. In any rational era, that would be earthshaking. Now it’s barely a blip. Over the past two years, we’ve become accustomed to headlines like “President’s Campaign Manager Convicted of Fraud” and “President’s Personal Lawyer Paid for Adult Actress’s Silence.” We’re numb to it all. But these are the sorts of developments that would, under normal circumstances, end a presidency.

They still might. Cohen admitted that he lied to Congress to support President Trump’s version of events. He notably did not claim that he did so at Trump’s request, or that Trump knew he would do it. But if Cohen’s telling the truth this time, then this conclusion, at least, is inescapable: The president, who has followed this drama obsessively, knew that his personal lawyer was lying to Congress about his business activities, and stood by while it happened.

Read: Michael Cohen’s astonishing claim about the Trump Tower meeting

And that’s not all. Cohen’s plea is only one shoe dropping in a boot warehouse. Who else lied to Congress about the pursuit of a hotel deal in Russia? Donald Trump Jr.? Did the president himself lie about it in his recent written answers to Mueller’s questions? (His lawyers claim that his answers matched Cohen’s.) Even if the pursuit of the hotel deal wasn’t criminal (and there’s no evidence that it was), everyone in Trump’s orbit who made statements about it—whether under oath or in interviews with the FBI—is in jeopardy today.

They’re not just in danger from Mueller, either. In just weeks, a Democratic majority will take over the House of Representatives. Control of committees will shift, and subpoenas will fly like arrows at Agincourt. Each hearing will present new terrible choices: Take the Fifth, tell uncomfortable truths, or lie and court perjury charges? Each subpoena is a new chance for frightened Trump associates to make new bad decisions like the ones that have felled Cohen and Manafort and Gates and Flynn and Papadopoulos.

I wouldn’t expect President Trump’s agitated tweets to stop anytime soon.