What did Donald Trump do today?

He got very confused about how supply and demand works. 

This morning, Trump tweeted out instructions for the world oil market:

EVERYONE, KEEP OIL PRICES DOWN. I’M WATCHING! YOU’RE PLAYING RIGHT INTO THE HANDS OF THE ENEMY. DON’T DO IT! 

This was apparently in response to the Iranian Parliament authorizing its military to close off the Straits of Hormuz to shipping. While no action has been taken yet, closing that channel would disrupt up to 20% of the world's oil supply. Even the threat of a future interruption could easily spur a rush to buy existing stocks or futures contracts. 

Trump is a graduate of the Wharton School at the University of Pennsylvania, although he's been caught lying about his performance there, which may explain why he's adamantly refused to release his grades. Even so, he must have taken Wharton's equivalent of an introductory economics course. In any such course, students are taught how in open and reasonably efficient markets, price is primarily a function of the relationship between supply and demand.

In this example, the equilibrium price is going down because of an increase in supply.

In other words, neither Trump nor anyone else can simply command "EVERYONE" to "KEEP OIL PRICES DOWN" regardless of whether there's an oil shortage. Businesses exist to make money—or to at least try to—and in a capitalist system they do not take orders from presidents to the contrary, no matter how loudly it's typed.

In reality, oil prices actually went down a little today, mostly because Iran responded to the weekend attack on its nuclear infrastructure with a relatively measured and limited response, signaling a willingness to de-escalate. That response took the form of a missile attack on a U.S. airbase in Qatar, for which Trump bizarrely thanked Iran. 

This is not the first time in recent weeks Trump has gotten confused about the extent of his powers over the entire world economy. He also commanded American companies to pay the sky-high taxes he imposed in the form of tariffs without raising prices. They declined. 

Why does this matter?

• Trump thinking he has the power to set worldwide oil prices by fiat would just be pathetic if he weren't also in a position to damage the American economy in so many other ways. 

• It's one thing to be relieved that an enemy didn't make a more serious attack against American military targets, but it's another fucking thing entirely to thank them for it.