This isn't an entirely unusual act for the president of the United States. He often takes to tweeting about morning television hosts, and the Morning Joe crew have frequently been the aim of his tweet attacks.
But this one was unusual for its brutal tone. Rather than take the typical path of tweeting that news hosts who say something bad about him are nothing more than "FAKE NEWS," Trump's tweet about Brzezinski was heavily tinted with sexism.
Now, again, this isn't an entirely unusual act for Donald Trump. Trump has a noted, on-the-record history of making sexist remarks.
But that he feels that he is in a position, as President of the United States, to make these public comments is more than a little disarming.
Around 9 a.m. ET, Trump tweeted that although he doesn't watch Morning Joe anymore, he hears the show "speaks badly of me." He proceeds to call host Joe Scarborough "Psycho Joe" while Brzezinski is "low I.Q. Crazy Mika."
Trump went on to tweet that Scarborough and Brzezinski allegedly went to his Mar-a-Lago resort in Florida "around New Year's Eve, and insisted on joining me." Brzezinski, the president tweeted, was "bleeding badly from a face-lift," and Trump "said no" to them joining him.
It's one issue for the president of the United States to publicly attack reporters for saying things he doesn't like.
It's a whole other issue for the president of the United States to publicly attack a woman based on her appearance.
Whether or not Brzezinski had a face-lift is beside the point. This is about Trump's apparent belief that the only thing that matters to and about a woman is how she looks.
To reiterate, Trump has a history of making alarmingly sexist comments. But as president, he has mostly restrained himself.
This week, however, the comments have come back.
On Tuesday, Trump interrupted a phone call with the Irish prime minister to comment on a female reporter's looks. This was a woman doing her job, and Trump stopped doing his job so he could tell her she had "a nice smile on her face."
Any woman can tell you how unsettling it is to have a man comment on your looks as you're trying to do your job (or walk down the street, or work out, or live your life). It's a reminder of patriarchal power, that no matter how hard you work, your only value is your appearance.
It's easy to write a Trump tweet off as something laughably ridiculous, but this kind of language wears women down as it continues to assert dominance.
Trump apparently feels comfortable enough as the most powerful man in the United States to go back to his old habits. But as president, his words have a very different effect. Children are hearing this. Young boys are hearing this and thinking that it's OK to treat women like this.
Teen boys are hearing this. Young men are hearing this. Grown men are hearing this.
When it comes from the president, that sort of talk is inherently approved. Men can point to him as an example: If the president can talk like that, why can't I?
On the other side, girls and women are seeing this. We are being told, again, that our only worth is our appearance. That everything else about us does not matter.
And the truth is, that hurts.