Richard Grenell officially started his job as the U.S. Ambassador to Germany on Tuesday, and it didn’t even take him a day to insult Germany on Twitter.

You might remember Richard Grenell from Mitt Romney’s presidential campaign. The openly gay spokesman was hired by the campaign to handle foreign policy messages, but was forced to resign after being attacked by anti-gay right wing conservatives.

At his confirmation hearings last year, one Democratic Senator brought up Grenell’s “litany of derogatory comments about women’s personal appearances” on Twitter, because that sort of conduct could hurt an ambassador’s ability to do their job, especially when they’re being sent to a country led by a woman. He was approved largely on party lines.

Since he has shown that he has no ability to think before he tweets, Grenell has already insulted Germany. On Tuesday, he instructed German businesses to stop doing business with Iran because the U.S. is pulling out of a nuclear arms control agreement the Obama Administration brokered.

As @realDonaldTrump said, US sanctions will target critical sectors of Iran’s economy. German companies doing business in Iran should wind down operations immediately. — Richard Grenell (@RichardGrenell) May 8, 2018

It turns out other countries don’t like being bossed around. His tweet received many indignant responses from German people, and has become a subject of discussion in German media.

“Good cooperation means that you do not drive a highly aggressive, ruthless policy towards our security interests and, before you even show up, you threaten the German economy,” said Bundestag member Omid Nouripour in a radio interview. “It’s just not a tone of cooperation.”

“It’s not up to me to teach the U.S. ambassador how to be diplomatic, but he does seem to need a bit of tutoring,” said Social Democratic leader Andrea Nahles.

Grenell even got some advice from Germany’s former ambassador to the U.S.

Ric: my advice, after a long ambassadorial career: explain your own country’s policies, and lobby the host country – but never tell the host country what to do, if you want to stay out of trouble. Germans are eager to listen, but they will resent instructions. — Wolfgang Ischinger (@ischinger) May 9, 2018

In response to the controversy, Grenell retweeted a tweet from Bush Administration official Ari Fleischer.

Note to all US Ambassadors: if you want good press coverage, defy the President who appointed you. Whatever you do, do NOT represent the position of the President of the US. https://t.co/S2nXXE1RmR — Ari Fleischer (@AriFleischer) May 9, 2018

In one sense, Fleischer is making a valid point: a White House that is reflexively opposed to international cooperation cannot be expected to do anything but bark orders at other countries.

On the other hand, a diplomat should carry out their mission… diplomatically. While obviously Trump doesn’t think that being a Twitter troll is disqualifying for a powerful and sensitive position, people all over the world can be forgiven for expecting better.