President Donald Trump has announced on Twitter that he has canceled his visit to Copenhagen after Denmark’s prime minister changed his idea of buying Greenland as ‘absurd.

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“Denmark is a very special country with incredible people, but based on Prime Minister Mette Frederiksen’s comments, that she would have no interest in discussing the purchase of Greenland, I will be postponing our meeting scheduled in two weeks for another time,” he wrote.

But he also thanked the Danish PM on Twitter for “being so direct,” in remarks to journalists as he departed the White House. Trump branded her comment as “nasty.”

“I thought the prime minister’s statement that it was absurd, that it was an absurd idea, was nasty. I thought it was inappropriate. All she had to do was say, ‘No, we wouldn’t be interested,'” Trump said.

“She’s not talking to me. She’s talking to the United States of America,” the president added. 

“You don’t talk to the United States that way.”

Earlier, Frederiksen shared “regret and surprise” at September’s state visit being postponed, as she reiterated once more that Greenland was not for sale.

“I had been looking forward to the visit and preparations were well underway,” Frederiksen told journalists in Copenhagen in a statement delivered in Danish and English. “It was an opportunity to celebrate Denmark’s close relationship to the US, which remains one of Denmark’s closest allies.”

She added, “This does not change the character of our good relations [with the US], and we will of course from Denmark continue our ongoing dialogue with the US on how we can develop our cooperation and deal with the many common challenges we are facing.”

Denmark’s Queen Margrethe II has invited Trump and the first lady, Melania Trump. Denmark’s state broadcaster quoted a royal spokesperson as saying that Trump’s announcement “came as a surprise.”

“That’s all we have to say about that,” the spokesperson added.

Former Danish Prime Minister Helle Thorning-Schmidt was more direct. “Is this some sort of joke?” she wrote on Twitter after Trump canceled the state visit.