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Michael Cohen can testify to Robert Mueller that Donald Trump was aware of the June 2016 Trump Tower meeting during which Russian officials promised dirt on Hillary Clinton, reports CNN. The question then becomes whether Cohen’s testimony is reliable, and whether Mueller can prove it. The answer to both questions is almost certainly yes.

Cohen’s apparent testimony merely fleshes the skeleton of a story we already knew. Former Trump aide Sam Nunberg has said, in an interview with Jake Tapper, that Trump knew about the meeting:

Tapper: Do you think that — Donald Trump says that — President Trump says he knew nothing about the meeting. Do you think that that’s true? Nunberg: No. Tapper: You don’t think that’s true? Nunberg: No. It doesn’t — and, Jake, I have watched your news reports. You know it’s not true. He talked about it a week before. And I don’t know why he did this. All he had to say was, yes, we met with the Russians. The Russians offered us something, and we thought they had something. And that was it. I don’t know why he went around trying to hide it. And he shouldn’t have.

Steve Bannon has said the same thing. (“The chance that Don. Jr did not walk these Jumos up to his father’s office on the 26th floor is zero.”) This is obvious. In a loosely structured campaign, with people coming in and out of Trump’s office at will, and all of them desperately vying for the boss’s approval, the notion that they could set up what they believed to be a meeting that would deliver devastating dirt on Crooked Hillary and not tell Trump what they had done is preposterous.

Indeed, the night the meeting was set up (but before it took place), Trump excitedly told a crowd, “I am going to give a major speech on probably Monday of next week and we’re going to be discussing all of the things that have taken place with the Clintons. I think you’re going to find it very informative and very, very interesting.”

After the meeting failed to produce the hoped-for dirt, the promised speech did not take place.

Cohen can testify that he was present when Trump was informed of the meeting.

Trump, who has lied about his dealings with Russia so many times that his word has grown completely worthless, has to resort to the defense of pulling down the value of hostile witnesses to his own level. Rudy Giuliani, Trump’s attorney, told CNN Thursday night, “[Cohen]’s been lying all week, he’s been lying for years.”

Years! Keep in mind that Cohen has been working for Trump until recently. The effort to impugn Cohen’s credibility naturally impeaches Trump’s own credibility. Neither man is especially trustworthy, but the preponderance of circumstantial evidence supports Cohen’s testimony.

One can see the ground already shifting in the defenses of Trump. Now his defenders deny that working cooperatively with Russians to obtain Russian dirt on Clinton amounts to collusion, or that such a thing is bad at all. “Look, I don’t think that it’s bad if campaigns are turning to foreign governments for dirt,” asserts Andrew McCarthy on Fox News, “It’s not collusion. It’s not something that’s impeachable; it’s icky, but that’s what this is.”

But if that’s the case, and Trump faces no legal liability for his secret collaboration with Russia, why didn’t he simply admit it all along? Why tell a series of lies and implicate his subordinates in those lies, exposing them to potential perjury charges? Perhaps because he has more to hide.