(CNN) On Thursday morning, President Donald Trump claimed a taped interview with NBC's Lester Holt in 2017 was somehow doctored to make him look bad.

As part of a broader attack on the so-called "fake news," Trump tweeted this: "When Lester Holt got caught fudging my tape on Russia, they were hurt badly!."

The reference is to a May 2017 interview between Trump and Holt in the days following Trump's firing of FBI Director James Comey. The Trump White House has insisted that Comey was let go because of a memo penned by Deputy Attorney General Rod Rosenstein laying out the various ways that the then-FBI director violated bureau policy with the way he acted during the 2016 election between Trump and Hillary Clinton.

Which is why it's notable that Trump said this under questioning from Holt

TRUMP: "Oh, I was gonna fire regardless of recommendation --"

HOLT: "So there was --"

TRUMP: "He made -- he made a recommendation, he's highly respected, very good guy, very smart guy, uh, the Democrats like him, the Republicans like him, uh, he made a recommendation, but regardless of recommendation, I was going to fire Comey, knowing there was no good time to do it. And in fact when I decided to just do it, I said to myself, I said, you know, this Russia thing with Trump and Russia is a made up story."

It's not clear what Trump is alleging about NBC and the tape of his interview -- which is, of course, intentional. Saying that the news network was "fudging" the tape is vague enough that the conspiracy theorists who want to believe Trump is "onto something" can do so. If Trump was forced to make an actual allegation about how NBC actually changed the tape [narrator voice: they didn't] the ridiculousness of his assertion would be plainly on display for all to see.

Look, don't believe me? Watch the tape. See if there is ANY evidence that the exchange above is in any way, shape or form has been altered at all by NBC. I've watched it 20-plus times. There is ZERO evidence of any doctoring.

Then, use your rational brain. And ask your brain these questions:

1) Would NBC really risk its credibility by "fudging" a taped interview between the President of the United States and its lead nightly news anchor?

2) If Trump had actual evidence (he doesn't) of a major broadcast network changing the nature of an answer he gave on something as consequential as the firing of Comey, why would he wait for 15 months to break that news? (He wouldn't, of course.)

What Trump is doing here with NBC isn't new. Remember that more than a year after the release of the "Access Hollywood" tape in which he was heard making a series of inappropriate remarks about women, Trump told at least one senator that he wasn't sure it was even his voice on that tape. (Worth remembering: He apologized for using "locker room" language in the tape when it was initially revealed.)

This is all of a piece with Trump's famous/infamous remark in a VFW speech last month in Kansas City : "Stick with us. Don't believe the crap you see from these people, the fake news. ... What you're seeing and what you're reading is not what's happening."

That is a truly remarkable statement. It's almost as if Trump, having convinced his supporters that everyone but him is a liar, is now trying to push the envelope even further: To persuade them that what they see and hear with their own eyes and ears isn't true.

What else could explain an attempt to discredit actual video evidence? Video/audio of you saying or doing things feels like the last frontier in Trump's assault on truth. It seems insane to argue that what you can see and hear is wrong or has been doctored in some meaningful way. It seems doubly insane to make that case when you offer zero proof other than vague references to how the tape was changed.

And yet, here we are. This is what happens when you elect someone whose entire political reason for being began in a conspiracy theory about President Barack Obama not being born in the United States. And when you allow someone to substitute opinions for facts. And when you stop believing that there is even such a thing as objective truth or non-alternative facts.

Questioning the legitimacy of video proof of his own mistakes is the logical next step of the weaponizing of untruth that Trump has pursued since he became a candidate for president in 2015. (And, in truth, long before he was an actual, announced candidate for president.) No one should be surprised. Everyone should be concerned.