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Moments before touching down in London for his first state visit to the United Kingdom, President Donald Trump on Monday attacked London Mayor Sadiq Khan, branding him a “stone cold loser” who reminded him of New York’s Mayor Bill de Blasio—the Democratic 2020 candidate and frequent Trump critic.

….Kahn reminds me very much of our very dumb and incompetent Mayor of NYC, de Blasio, who has also done a terrible job – only half his height. In any event, I look forward to being a great friend to the United Kingdom, and am looking very much forward to my visit. Landing now! — Donald J. Trump (@realDonaldTrump) June 3, 2019

The battery of insults followed a scathing op-ed Khan published in the Guardian over the weekend that condemned the UK’s decision to hold the formal state visit. In it, he compared Trump to European dictators of the 1930s and ’40s. “Donald Trump is just one of the most egregious examples of a growing global threat,” he wrote before calling attention to the rise of far-right groups around the world.

“That’s why it’s so un-British to be rolling out the red carpet this week for a formal state visit for a president whose divisive behaviour flies in the face of the ideals America was founded upon—equality, liberty and religious freedom,” Khan continued.

A spokesperson for Khan’s office responded to Trump’s “childish insults” by saying they should be “beneath the president of the United States.”

But attacking the mayor was just the start. Trump then aimed his anger at the television offerings in the UK, lamenting that CNN was the primary US news source available. The president’s favorite network, Fox News, was pulled off the air in 2017 due to lack of viewership. The Rupert Murdoch–owned channel had also been under scrutiny for breaking the UK’s impartiality rules for broadcasters.

Just arrived in the United Kingdom. The only problem is that @CNN is the primary source of news available from the U.S. After watching it for a short while, I turned it off. All negative & so much Fake News, very bad for U.S. Big ratings drop. Why doesn’t owner @ATT do something? — Donald J. Trump (@realDonaldTrump) June 3, 2019

Trump’s irritability at the outset of his three-day visit, which will involve tea with the queen and events commemorating the 75th anniversary of D-Day, is likely to be further inflamed by the mass protests—along with the blimp depicting a diaper-wearing Trump—that are expected during his stay in the UK. From there, Trump will travel to Ireland and France.