His confirmation as ambassador to Germany took a while, but when Richard Grenell arrived in Berlin in May he wasted no time riling up his new hosts. On his first day on the job, he tweeted that German companies doing business in Iran should “wind down operations immediately” because President Trump had decided to unilaterally withdraw from the painstakingly negotiated nuclear deal with Iran.

Germans were not amused by an ambassador telling them what to do, but that hardly deterred our man in Berlin. What he did next was to give an outrageous and insulting interview over the weekend to Breitbart, summarized thus by the alt-right mouthpiece: “Trumpian U.S. Ambassador to Germany Richard Grenell has expressed great excitement over the wave of conservatism in Europe, saying he wants to ‘empower’ leaders of the movement.”

Mr. Trump was no doubt highly pleased by his envoy, a former United Nations spokesman, Mitt Romney campaign aide and Fox News contributor, whose confirmation was long held up by congressional critics over his history of provocative tweets, including several derogatory of the appearance of prominent women.

But ambassadors do not represent a president; they represent a state, and they are not supposed to go around “empowering” nationalist movements or far-right ideologies in other countries. The Germans were furious. The new ambassador is behaving “not like a diplomat, but like a far-right colonial officer,” fumed Martin Schulz, the former European Parliament president.