Lock them up? Donald Trump and Michael Flynn. Photo: George Frey/Getty Images

It has never been clear what crimes, if any, Donald Trump might have personally committed in the course of the Russia scandal. But in the 24th paragraph of a new NBC News report on the investigation is a sentence that indicates Robert Mueller’s cleanest shot — so far — at proving illegality by the president. Mueller, NBC reports, “appears to be interested in whether Trump directed [Michael Flynn] to lie to senior officials, including Pence, or the FBI, and if so why, the sources said.”

This could be very important. Here’s what it means.

In December 2016, Flynn sat at the center of hidden diplomacy between the Trump transition team and Russia. The departing Obama administration was putting into place sanctions to punish Russia for its criminal theft of emails. The Trump team was quietly telling Russia not to retaliate because it would reverse or undermine those sanctions. Flynn conveyed this message to Russian ambassador Sergey Kislyak in December. The next month he denied doing so to FBI agents.

Two days after that, Sally Yates, the acting attorney general, met with White House counsel Don McGahn and told him about Flynn’s lie, which she had learned of through FBI surveillance of Russia. The danger of the lie was extreme. Since the Russians were privy to the conversation Flynn had denied ever having, they knew he was lying, and thus had powerful blackmail leverage over him.

And yet, despite having been informed that the incoming national security adviser was an extreme security risk, the White House responded with strange lethargy. Flynn remained on the job for 18 more days, and was finally fired, supposedly for lying to Vice-President Mike Pence. Trump nonetheless praised Flynn effusively, and reportedly later conveyed the message he should “stay strong.”

There are many questions around this episode, but the most pertinent ones concern why Flynn would behave so recklessly. He took a big risk by speaking with the Russians, violating the Logan Act, which prohibits private citizens from “influenc[ing] the measures or conduct of any foreign government” or “defeat[ing] the measures of the United States.” Flynn’s career in intelligence work would have made him perfectly aware of the high likelihood that his conversation was being surveilled. He took a second additional risk by allegedly lying about this to the FBI.

News reports have focused on the possibility that Trump ordered Flynn’s outreach to Russia. It makes sense (to whatever extent anything in Trumpworld makes sense) that Flynn would get the president-elect’s approval before communicating such an important message. On the other hand, there is also some debate about the severity of Trump’s exposure to a violation of the Logan Act, which is extremely old and has not been tested in court.

But NBC is raising a different, and more serious, possibility: that Trump also instructed Flynn to lie to the FBI about his conversation. That scenario would explain a lot. It would explain why Flynn took not one but two gigantic legal risks. It would explain why the White House took so long to fire him, why Trump asked James Comey to let Flynn off the hook and then fired him when he failed to promise to do so, and why Trump continued to signal his affection for Flynn even afterward.

Flynn might have done both legally dubious things of his own volition. He is a pretty unstable character, after all. But it seems at least as likely that he felt empowered to take such obvious chances because the incoming president offered him cover.

If this is what happened, the legal violation would not be ambiguous at all. Lying to the FBI is an obvious crime. Even the tortured rationales Trump’s defenders are making on his behalf — that he didn’t obstruct justice by firing Comey, and would also not be obstructing justice by shutting down Mueller’s investigation — would be irrelevant in the face of this action. (Obviously, they would just invent new rationales. But still.)

We don’t know whether Trump did tell Flynn to lie. And if it happened, we don’t know whether Flynn has actually testified to this effect. But for the first time, we have a clear line of sight to a potential act of undeniable illegality by President Trump.