Davos, Switzerland - European Commission President Ursula von der Leyen vowed on Tuesday an response to Donald Trump's threats over Greenland, as the US president said he was ready to hold a meeting in Davos about the Arctic island.

In a speech to the World Economic Forum in the Swiss ski resort, von der Leyen warned that Trump risked plunging US ties with the European Union into a "downward spiral" over the autonomous Danish territory.

Trump, who will address the annual gathering of global elites on Wednesday, has put the transatlantic alliance to the test with his attempted landgrab.

Europe is weighing countermeasures after the Republican threatened to impose tariffs on eight European countries over the Greenland standof, with EU leaders set to hold an emergency summit on Greenland in Brussels on Thursday.

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"The proposed additional tariffs are a mistake, especially between long-standing allies," von der Leyen told the meeting of world business and political leaders.

"Plunging us into a downward spiral would only aid the very adversaries we are both so committed to keeping out of the strategic landscape. So our response will be unflinching, united, and proportional."

Trump pressed on with his Greenland campaign on Truth Social, posting a fake photo of himself planting a flag in a rock and ice landscape next to a sign reading "GREENLAND - US TERRITORY EST. 2026."

He later wrote he had a "very good" call with NATO secretary-general Mark Rutte over mineral-rich Greenland.

"I agreed to a meeting of the various parties in Davos, Switzerland," he said late on Monday, before posting a screenshot of a humiliatingly obsequious text message from Rutte.