President Trump has canceled an upcoming trip to Denmark over the country’s refusal to discuss selling Greenland to the United States. On Sunday, Trump confirmed to reporters his interest in purchasing the autonomous Danish territory and did not rule out trading a U.S. territory for the island. “Essentially, it’s a large real estate deal,” Trump said. Danish politicians across the political spectrum expressed disbelief over Trump’s sudden cancellation. Prime Minister Mette Frederiksen called his idea to purchase Greenland “absurd.” She also told reporters, “Thankfully, the time where you buy and sell other countries and populations is over.” A former business minister asked on Twitter: “Are parts of the U.S. for sale? Alaska? Please show more respect.” On Monday, Trump tweeted a photo of a shiny gold Trump skyscraper photoshopped onto an image of a Greenland town, and wrote, “I promise not to do this to Greenland!” Trump is said to be interested in Greenland’s abundant natural resources and geopolitical importance, but the island is also at the center of the climate crisis.

Earlier this month, Greeland’s ice sheet experienced its largest single-day melt in history. In July, the hottest month ever recorded, Greenland’s ice sheet lost 197 billion tons of ice, the equivalent of around 80 million Olympic swimming pools. Experts say that in addition to rising sea levels around the world, the receding ice could expose toxic nuclear waste left at U.S. military sites during the Cold War.