What did Donald Trump do today?

He whipsawed between taking orders from Saudi Arabia and Russia on the oil field attack.

Yesterday, Saudi oil facilities were set ablaze by an apparent drone attack. As much as 5% of the world's oil production capacity was affected, and oil prices spiked immediately.

The obvious suspects were either Iran or the Iranian-backed Houthi movement in Yemen's civil war. Saudi Arabia is essentially fighting against the Houthis in that war, thanks to de facto Saudi ruler Crown Prince Mohammed bin Salman. Trump has bent over backwards to defend bin Salman in the past. Iran denied responsibility, and the Houthis claimed it, but the opposite may be true.

Trump gave up any diplomatic influence over Iran when he unilaterally withdrew the United States from an international agreement to control Iran's nuclear program, although recently he'd been trying to entice Iran back into a deal that would allow him to save face before the 2020 elections. 

But Trump responded to the attack by tweeting that the United States would intervene when the Saudi government told him what to do.

Asked about this today, Trump explained that he had to intervene on the Saudis' terms because they'd bought the privilege.

But we would certainly help them.  They’ve been a great ally.  They spend $400 billion in our country over the last number of years.  Four hundred billion dollars.  That’s a million and a half jobs.  And they’re not ones that, unlike some countries, where they want terms; they want terms and conditions.  They want to say, “Can we borrow the money at zero percent for the next 400 years?”  No.  No.  Saudi Arabia pays cash.

This isn't the first time that Trump has rationalized doing the Saudis' bidding over money. Faced with the murder of Washington Post journalist Jamal Khashoggi, Trump repeatedly denied his own government's finding that it had been ordered by the Crown Prince, and then insisted that he was powerless to act because the Saudis had promised to buy weapons from American companies.

Trump, as a private citizen, is deeply financially entangled with the Saudi royal family—as is his son-in-law, Jared Kushner, who Trump appointed to oversee a Middle East peace plan.

However, the Trump White House did sound one note of caution about the possibility of engaging Iran in a military conflict this morning—but only after Russia, which is aligned with Iran, pointedly warned Trump to "avoid any hasty steps or conclusions."

Why is this a bad thing?

• The United States should choose its military engagements based on its own best interests, not whichever foreign power has the most influence over its president.

• American foreign policy should not be for sale at any price.