Washington DC - Vice President JD Vance warned Europe on Thursday to take Donald Trump "seriously" on Greenland as the president ramps up threats against the Danish-ruled Arctic territory.

Vance accused fellow NATO member Denmark and the rest of Europe of failing to do enough to protect the strategically-located island from the designs of Russia and China.

European capitals have been scrambling to come up with a coordinated response after the White House said this week that Trump wanted to buy Greenland and refused to rule out military action.

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"I guess my advice to European leaders and anybody else would be to take the president of the United States seriously," Vance told a briefing at the White House when asked about Greenland.

Vance urged them to respond in particular to Trump's insistence that the US needs the island for "missile defense," with Moscow and Beijing increasing military activities nearby and the Arctic ice melting due to climate change.

"So what we're asking our European friends to do is to take the security of that land mass more seriously, because if they're not, the United States is going to have to do something about it," Vance said.

"What that is, I'll leave that to the president as we continue to engage in diplomacy with our European friends and everybody on this particular topic."

Secretary of State Marco Rubio is due to meet officials from Denmark and Greenland next week.

An emboldened Trump has long talked about acquiring Greenland but has ramped up his threats since the US military operation to topple Venezuela's ruler Nicolás Maduro last week.

The threats have infuriated Denmark, a founding NATO member and longtime US ally, and set alarm bells ringing across Europe.

An invasion would pit Washington against fellow NATO member Denmark and threaten to blow up the entire military alliance, which is based on a mutual self-defense clause.

A flurry of diplomacy is underway as Europeans try to head off a crisis while at the same time avoiding the wrath of Trump, who is nearing the end of his first year back in power.

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British Prime Minister Keir Starmer "set out his position on Greenland" during a call with Trump on Wednesday and then said more could be done to protect the "high Arctic" from Russia in a second call on Thursday, Downing Street said.

Vance was meeting British Deputy Prime Minister David Lammy in Washington for talks that would focus on the Ukraine war, but where Greenland could come up.

European countries have stood in solidarity with Denmark, with key leaders issuing a joint statement with Copenhagen saying it was for Denmark and Greenland alone to decide its fate.

French President Emmanuel Macron even warned on Thursday that the US was "turning away" from allies in some of his strongest criticism yet of Trump's policies.

Macron said "global governance" was key at a time when "every day people wonder whether Greenland is going to be invaded."

Vance, however, has long been critical of Europe over defense issues, saying in a leaked chat with senior US officials last year that he hated "bailing out" the continent.

The Trump administration's new US national security strategy launched a brutal attack on Europe in December, describing it as facing "civilizational erasure" from migration and calling for "cultivating resistance" among right-wing parties.