“Never interfere with your enemy when he is making a mistake,” Napoleon said. It’s a lesson neither President Trump nor “The Squad” seems to have learned.

Going into the weekend, the press was chock-full of stories about the Democratic civil war. Nancy Pelosi sniped at Alexandria Ocasio-Cortez, progressives disparaged “moderates.” Republicans were popping popcorn, watching the Dems destroy each other.

Rather than stay silent, Trump tweeted himself into the conversation, saying that the four far-left Democrats should “go back” to the countries they came from.

Besides being factually off — three of the four are American-born, all are citizens and where do they “go back” to, Detroit? — the language was incendiary and offensive.

Whatever point he was trying to make about their criticisms of the United States and their rhetoric on Israel was lost to his indecency. The media narrative became all about Trump and which Republicans would criticize him.

Then it was “the Squad’s” turn to step on their own moment. Reps. AOC, Ilhan Omar, Ayanna Pressley and Rashida Tlaib held a press conference at which they erased any sympathy they might have garnered.

It wasn’t enough to object to Trump’s tweet: They had to accuse him of murdering children, complain that he won’t provide universal health care, that he is “weak.” Pressley wouldn’t even call him president, referring to “the occupant of the White House.” It’s time for impeachment, they all agreed.

Mr. President, there’s a reason 51% of Americans approve of the way you’re handling the economy, yet your favorability rating is only 43%, per the RealClearPolitics poll averages. It’s because of tweets like the one you sent out this weekend.

“The Squad” demonstrated Monday just how radical they are all on their own. Don’t get in their way. Sit back with some popcorn and enjoy the self-destructive show.