What did Donald Trump do today?

He said media companies that aren't nice enough to him should be punished.

Trump found plenty of time for tweeting during the first day of his state visit to the UK, including a threat against the parent company of CNN. He wrote, "I believe that if people stoped using or subscribing to @ATT, they would be forced to make big changes at @CNN."

AT&T merged with CNN in 2017, although Trump—already easily triggered by the politically centrist network—tried to block the merger in court. Ironically, the fact that the head of the executive branch tried so publicly to block a business deal for political reasons probably made it easier for the merger to proceed. 

This is not the first time that Trump has tried to drive customers away from American companies that he feels aren't sufficiently supportive.

It's not entirely clear what (if anything) spurred the latest outburst, but Trump is apparently angry that the press is reporting on his ongoing debacle over insulting Meghan Markle, and has settled on CNN as the scapegoat. Trump, 72, doesn't travel well and is prone to odder-than-usual behavior when overseas.

Why is this a bad thing?

• You can have a free press, or one that says nice things about the government to stay out of trouble, but not both.

• A president who can't control his temper long enough to get through the first day of a diplomatic trip isn't up to the job.