When President Trump flatly declared on Twitter that his son held that Trump Tower meeting in the full expectation of receiving dirt on Hillary Clinton, he may have done more than concede that collusion did, in fact, take place. He may have also inadvertently pointed to a motive for his repeated efforts to obstruct the Russia investigation — possibly strengthening the case that he obstructed justice.

Much of this morning’s chatter about Trump’s Twitter admission over the weekend focuses on two important facts about it, but not on that one. In the tweet, Trump stated forthrightly that the Trump Tower gathering “was a meeting to get information on an opponent.” However, we know from Donald Trump Jr.’s emails before the meeting that he — along with son-in-law Jared Kushner and campaign chair Paul Manafort — took this meeting in the full expectation of getting “information on an opponent” that would be furnished by the Russian government.

As many news accounts and analyses point out, Trump has now flatly conceded to that collusion more directly than ever before. As those accounts also point out, in so doing, Trump has also revealed that the statement he helped dictate about this meeting in the summer of 2017 — which claimed it was primarily about adoptions — was a lie.

But what’s also notable is why Trump tweeted this. He was responding to a report in The Post that said this:

Trump has confided to friends and advisers that he is worried the Mueller probe could destroy the lives of what he calls “innocent and decent people” — namely Trump Jr. … As one adviser described the president’s thinking, he does not believe his son purposefully broke the law, but is fearful nonetheless that Trump Jr. inadvertently may have wandered into legal ­jeopardy.

Publicly, at least, Trump is denying that he believes his son is in legal jeopardy. In his tweet, he claimed that this report is “a complete fabrication,” adding that the meeting was “totally legal and done all the time in politics.”

But the actions of Trump himself — and of his lawyers — cast doubt on this claim, and this points to a huge hole in the current spin that Team Trump is attempting. It’s this: Trump and his lawyers keep claiming there was nothing wrong with this meeting — but they keep lying about it.

The fact that Trump helped dictate the statement falsifying the meeting’s rationale is only the most glaring example of this. Additionally, Trump’s lawyers argued in their recent memo to special counsel Robert S. Mueller III that this Trump statement about the meeting was “short, but accurate.” (We knew that was a lie, but now Trump himself has now essentially admitted to it.)

And in the very tweet which admits that collusion took place, Trump also falsely claims that meetings like this (to get oppo on an opponent) are “done all the time in politics,” which absurdly airbrushes out of the picture entirely the source of this oppo, i.e., the Russian government.

It is possible, of course, that members of Team Trump only lied repeatedly about the meeting because they thought it was politically, and not legally, problematic. But it’s more likely that The Post’s reporting is correct — that Trump does worry about legal jeopardy. This is reinforced by the fact that Trump keeps pretending, as he did in this tweet, that the very thing that may make this meeting legally problematic — the Russian government’s role — never happened. And if Trump does recognize that, it would provide a reason for trying to obstruct the probe.

“The obstruction case against Trump is more solid if there is strong evidence that he recognizes legal jeopardy,” Daniel Hemel, an assistant law professor at the University of Chicago who recently co-published a useful scholarly exploration of presidential obstruction of justice, told me this morning.

To be clear, as Hemel points out, even if Trump did recognize legal jeopardy, it could still be very hard to prove that Trump obstructed justice. Trump has tried to scuttle the investigation in all kinds of ways, from firing his FBI director to demanding that his attorney general protect him from the probe to ordering the firing of Mueller. But to show criminal obstruction of justice, Mueller would have to demonstrate that Trump acted with “corrupt intent” in doing those things — say, for the express purpose of protecting his cronies (such as his son) from investigation.

Trump may have done some or all these things because he feared that his son is in jeopardy, or more broadly because he believes the Trump Tower meeting (and any other collusion that may have occurred) may implicate his whole campaign in potentially illegal behavior. But we don’t know that, and it has to be proved.

“This doesn’t bring us all the way,” Hemel says. “We have a reason for him to do it. But that’s not the same thing as intent. This allows us to generate a hypothesis about what may have been in Trump’s head. But Mueller would still want more. You’ve got the two dots. But you still have to connect them.” So we have no idea whether Mueller will conclude that Trump committed criminal obstruction, and beyond this, even if he did, he almost certainly would not prosecute the sitting president.

Still, the New York Times reports this tantalizing nugget today:

People close to the president believe that he may be increasing his legal jeopardy by continuing to speak publicly about sensitive matters even as his campaign is under investigation for possible collusion with Russia and he himself is under scrutiny for possible obstruction of justice.

This strongly suggests Trump’s own team privately worries he is supplying a motive for obstruction. Trump’s efforts to scuttle the investigation are continuing — he recently called on his attorney general to shut it down. And in this context, Trump’s admission that collusion did, in fact, take place might help explain why he has continued to do that. As Hemel told me: “Trump is making Mueller’s case for him.”

Or, as Adam Davidson puts it, Trump has at this point “openly admitted to attempted collusion, lying, and a coverup.” Which means that the case against him — politically for sure, and perhaps legally as well — has just gotten stronger.