European Commission President Ursula von der Leyen vowed on Tuesday an "unflinching" 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 demand to take over Greenland.

Europe is weighing countermeasures after the US president threatened to impose tariffs on eight European countries over the Greenland standoff – although Washington has said any retaliatory levies would be "unwise".

"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."

Europe "must respond" to any trade war, Danish Prime Minister Mette Frederiksen later told her parliament, adding: "We are compelled to do so".

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

He later wrote he had 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 – after telling reporters he did not think European leaders would "push back too much" on his attempt to buy the vast island.

EU leaders will hold an emergency summit on Greenland in Brussels on Thursday.

Trump vs Macron

French President Emmanuel Macron also spoke at Davos on Tuesday, with his relations with Trump having hit a new low.

Wearing sunglasses due to an eye condition, Macron said the European Union should not bend to "the law of the strongest" and that it was staggering the bloc was having to contemplate using its "anti-coercion instrument" against the United States.

"We do believe that we need more growth, we need more stability in this world, but we do prefer respect to bullies," Macron said, speaking in English. "We do prefer science to (conspiracies) and we do prefer rule of law to brutality."

Trump threatened 200 percent tariffs on French wine and champagne over France's intention to decline an invitation to join his "Board of Peace", aimed at resolving international conflicts.

Analysts have likened the board – where a permanent spot will cost $1 billion, according to Trump – to a pay-to-play version of the UN Security Council.

Trump confirmed Monday that Russian President Vladimir Putin was one of various world leaders invited to join.

As for Macron, Trump told reporters "nobody wants him" as he will "be out of office very soon".

Macron has instead sent a message to Trump to propose a G7 summit in Paris on Thursday on Greenland, as well as ways to end Russia's conflict with Ukraine, with Copenhagen, Moscow and Kyiv attending on the sidelines.

The Kremlin said Russian envoy Kirill Dmitriev plans to meet members of the US delegation in Davos – the first to head to the mountain resort since Russians were excluded from the gathering following the Russian-Ukraine in 2022.

China slams 'law of the jungle'

Other prominent world leaders addressing the WEF on Tuesday included Chinese Vice Premier He Lifeng.

"A select few countries should not have privileges based on self-interest, and the world cannot revert to the law of the jungle where the strong prey on the weak," He said, without naming any country.

Canadian Prime Minister Mark Carney, who has sought to reduce his country's reliance on the United States in its own tariffs feud with Trump, also speaks in Davos.

Other flashpoints on the WEF agenda include the crises in Venezuela, Gaza, Iran – and Ukraine.

Ukraine President Volodymyr Zelenskyy warned Tuesday that he feared the furore over Greenland could divert attention.

"I'm worried about any loss of focus during a full-scale war," Zelensky told reporters, adding that the two crises should not be seen as "interchangeable".