European Council President Donald Tusk expressed a frustration that’s been bubbling up across Europe this week when he said of President Trump, “with friends like that, who needs enemies?”

Why it matters: Outraged that Trump spurned their pleas on the Iran deal, fearing the prospect of U.S. sanctions on steel and aluminum and at odds with Trump on key issues like climate change and the U.S. embassy move in Israel, Europe’s leaders are warning they could go their own way.

“Very senior” U.K. official to the BBC: "The Americans can't expect us to follow them round with a dustpan and brush putting Humpty Dumpty back together again."

to the BBC: "The Americans can't expect us to follow them round with a dustpan and brush putting Humpty Dumpty back together again." French finance minister Bruno Le Maire: "Do we want to be vassals who obey decisions taken by the United States while clinging to the hem of their trousers?"

Bruno Le Maire: "Do we want to be vassals who obey decisions taken by the United States while clinging to the hem of their trousers?" German chancellor Angela Merkel last week: “It’s no longer the case that the United States will simply just protect us. Let’s face it: Europe is still in its infancy with regard to the common foreign policy. That is the task for the future.”

This isn't the first time Trump has ruffled European feathers — calling NATO "obsolete" and leaving the Paris climate accord are other notable examples — but the Iran decision hit Europe both in the heart and in the wallet.

“The reaction is reflective of a sense in Europe that the Trump administration is really assaulting the values Europe is built on — multilateralism, cooperation and trade. In some ways it’s an emotional response.”

— Erik Brattberg, director of the Carnegie Endowment's Europe program

So what is likely to come from the European outrage?

The European Commission announced today it would revive a so-called blocking regulation that could offer European companies limited protections from U.S. sanctions. But French President Emmanuel Macron essentially ruled out further action, saying, “We won’t start a strategic trade war against the U.S. about Iran."

it would revive a so-called blocking regulation that could offer European companies limited protections from U.S. sanctions. But French President Emmanuel Macron essentially ruled out further action, saying, “We won’t start a strategic trade war against the U.S. about Iran." It could be a different story if Trump hits the EU with tariffs on June 1, Célia Belin of Brookings notes: "It's one thing to take a decision that disregards European interests. It's another thing to take a decision that attacks European interests."

What to watch for...