What did Donald Trump do today?

He blustered about destabilizing NATO because Germany spoke honestly about his war in Iran.

Earlier this week, German chancellor Friedrich Merz said this about the current state of the Iran War, in which Iran enjoys a stronger position than it had before Trump launched attacks, while Trump is desperate for a face-saving way of backing down: 

The Iranians are obviously very skilled at negotiating, or rather, very skilful at not negotiating, letting the Americans travel to Islamabad and then leave again without any result. An entire nation is being humiliated by the Iranian leadership, especially by these so-called Revolutionary Guards. And so I hope that this ends as quickly as possible.

Merz saying that Trump was being humiliated by Iran was apparently a worse provocation than the actual humiliation, and in response, Trump vowed to start pulling American forces out of Germany.

Asked about it today at his vacation resort in Florida, Trump doubled down, saying that "We're going to cut way down, and we're cutting a lot further than 5,000."

American forces in Europe are there for the benefit of the United States, not just its European allies. The installations where American troops and aircraft are stationed allow the United States to project its military force much further than it otherwise could. Trump himself was outraged when, for example, Spain—which hosts only about 3,800 American troops—refused to allow him to use its airbases to conduct attacks on Iran. Trump fumed in the media about imposing an embargo on Spain before, apparently, forgetting about it.

Trump has made no secret of his contempt for NATO, the basis for those joint security arrangements, and—outside of demands that European countries join in wars he launched without consulting them, or help him escape from the consequences—has looked for excuses to degrade the United States' military alliances with its traditional allies wherever possible. 

The main benefactor of these efforts is the Putin regime in Russia. Trump is personally, financially, and politically beholden to Putin, who has interfered in American elections to help him.

Why does this matter?

• American national security is more important than Donald Trump's ego, or the favors he owes.