On Friday the world witnessed one of the most astonishing spectacles in White House history.

American presidents have surely dressed down besieged allies behind closed doors; never before has it happened on live television. This break with any prior presidential diplomacy must be seen to be believed.

What unfolded between Ukrainian president Volodymyr Zelensky and President Donald Trump and Vice President J.D. Vance turned into a political Rorschach test.

For Trump’s base, the 50-minute exchange was proof positive of America First foreign policy—an ungrateful freeloader gets upbraided by the populist tribune.

For Americans who still cling to the now unfashionable notion that the international system should be ruled by rules and not might, Friday’s incident was a horror.

From the perspective of Europe, it’s the beginning of the end of the transatlantic alliance.