Donald Trump has delivered a stern message to his hosts in the United Kingdom.

He don’t need no stinkin’ diplomacy.

The president of the United States landed in London and then immediately hurled an insult at that city’s presiding elected official, Mayor Sadiq Khan, who he called a “stone cold loser.”

Oh, yes. He also said that Mayor Khan is doing a “terrible job as mayor” and has been “foolishly nasty to the visiting president of the United States.”

I suppose I need to mention that Khan is a Muslim, the first Muslim ever elected mayor of London. Khan also has taken umbrage at the president’s travel ban to the United States by all Muslims, which I suppose means that Khan can’t ever visit the former Colonies on official business. I mean, it’s not as though there might be some business to be done with the UK’s stellar political, economic and military ally … correct?

The president won’t listen to anyone, but he needs to understand something about diplomacy. It’s OK to think certain things about politicians, or perhaps say things in private to them. Why unleash these Twitter tirades into the universe, entering those epithets into the public domain and insulting the mayor of one of the world’s great cities?

What’s more, the president relies solely on empty platitudes, never once citing a specific example of why a fellow elected official is doing such a “terrible job.” That’s how this POTUS rolls, as we Americans have learned all too well.

Sadiq Khan isn’t the “stone cold loser” in this instance, Mr. President.

You are!