United States President Donald Trump has said acquiring Greenland, a Arctic territory held by Denmark, is a national security priority and that it must own the island to prevent Russia or China from taking it.
The shortest route from Europe to North America runs via Greenland, making it important for the US ballistic missile early-warning system.
Trump vowed on Saturday to implement a wave of increasing tariffs from February 1 on EU members Denmark, Sweden, France, Germany, the Netherlands and Finland, along with Britain and Norway, until the US is allowed to buy Greenland - a step major EU states decried as blackmail.
In a post on X, Von der Leyen said on Sunday she had discussed the developments with NATO Secretary-General Mark Rutte, Britain's Prime Minister Sir Keir Starmer, French President Emmanuel Macron, German Chancellor Friedrich Merz and Italian Prime Minister Giorgia Meloni.
"We will always protect our strategic economic and security interests," she said.
"We will face these challenges to our European solidarity with steadiness and resolve."
Starmer spoke to Trump on Sunday after talking to the leaders of Denmark, the EU and NATO, to say he believed "applying tariffs on allies for pursuing the collective security of NATO allies is wrong".
A Downing Street spokesperson said Starmer held phone calls with Danish Prime Minister Mette Frederiksen, European Commission president Ursula von der Leyen and NATO secretary general Mark Rutte. He then spoke to Trump.
"In all his calls, the Prime Minister reiterated his position on Greenland. He said that security in the High North is a priority for all NATO allies in order to protect Euro-Atlantic interests," the spokesperson said.
Danish Prime Minister Mette Frederiksen said in a written statement she was heartened by the consistent messages from the rest of the continent, adding: "Europe will not be blackmailed".
The shortest route from Europe to North America runs via Greenland, an Arctic territory held by Scandinavian country Denmark. Photo: Reuters
EU scrambles to avert Trump tariffs
European Union ambassadors reached broad agreement on Sunday to intensify efforts to dissuade Trump from imposing tariffs on European allies, while also preparing retaliatory measures should the duties go ahead, EU diplomats said.
EU leaders are set to discuss options at an emergency summit in Brussels on Thursday. One option is a package of tariffs on €93 billion (NZ$187 billion) of US imports that could automatically kick in on February 6 after a six-month suspension.
The other is the so far never used "Anti-Coercion Instrument", which could limit access to public tenders, investments or banking activity or restrict trade in services, in which the US has a surplus with the bloc, including in digital services.
The tariff package appeared to command broader support as a first response than anti-coercion measures, where the picture was currently "very mixed", according to an EU source.
European Council president Antonio Costa, who chairs EU summits, said in a social media post that his consultations with EU members had shown their strong commitment to support Denmark and Greenland and readiness to defend against any form of coercion.
Danish Foreign Minister Lars Lokke Rasmussen, visiting his Norwegian counterpart in Oslo, said Denmark would continue to focus on diplomacy, referring to an agreement Denmark, Greenland and the US made on Wednesday to set up a working group.
"The US is also more than the US president. I've just been there. There are also checks and balances in American society," he added.
The eight targeted countries, already subject to US tariffs of 10% and 15%, have sent small numbers of military personnel to Greenland.
"Tariff threats undermine transatlantic relations and risk a dangerous downward spiral," they said in a joint statement published on Sunday, adding they were ready to engage in dialogue, based on principles of sovereignty and territorial integrity.
European 'weakness'
European "weakness" necessitates US control of Greenland for global stability, US Treasury Secretary Scott Bessent said on Sunday - even as some lawmakers sounded alarms about the Trump administration's effort to acquire the territory.
Speaking on NBC's Meet the Press programme, Bessent said taking ownership of Greenland is crucial in a geopolitical chess match with Russia and China.
"We are the strongest country in the world. Europeans project weakness. US projects strength."
As tensions with the EU escalated on Sunday, Bessent said he believed European leaders would ultimately "come around" to the idea of US control of Greenland.
"I believe that the Europeans will understand that this is best for Greenland, best for Europe, and best for the United States."
Bipartisan opposition
The US Treasury chief said he had not recently discussed with Trump whether he was still considering using emergency powers to justify using force to take Greenland.
But doing so would be "ridiculous" because there is no emergency in Greenland, said Senator Rand Paul, a Kentucky Republican who chairs the US Senate Homeland Security Committee.
"The idea by the secretary that, oh, this is to prevent an emergency - now we're declaring emergencies to prevent emergencies?" Paul, who has long been a vocal opponent of aggressive US efforts overseas, said on Meet the Press.
The Senate Homeland Security Committee may push a war powers resolution limiting Trump's ability to use force, or a resolution challenging his use of tariffs, Senator Tim Kaine, a Virginia Democrat, said in the same interview.
Paul was not the only Republican on Sunday to challenge his party's president. US Representative Mike Turner, an Ohio Republican, said the tariff gambit could threaten relationships with NATO allies.
"This is not 'The Art of the Deal,'" Turner said on CBS' Face the Nation programme, referencing the title of Trump's 1987 book. "This is more like 'The Dating Game.' ... This certainly isn't the type of language someone should be using when asking someone to join you in a partnership."
But Texas Republican Senator John Cornyn characterised Trump's tariff threat as a negotiating tactic.
"Sometimes he believes in strategic ambiguity and talks in terms that get people's attention, but ultimately I think there's a deal to be made," Cornyn said on the Fox News Sunday programme.
Other lawmakers, including Senators Chris Van Hollen, a Maryland Democrat, and Ted Cruz, a Texas Republican, pointed to Greenland's natural resources as potential motivation for acquiring it, although they diverged on whether Trump has made a credible argument for the US to absorb the territory.
Cruz, speaking on Fox News' Sunday Morning Futures programme, cited Greenland's minerals as one of the "enormous economic benefits" of acquiring it, although he also pointed to the country's strategic location. "It is overwhelmingly in the US interest to acquire Greenland," Cruz said.
Speaking on ABC News' This Week programme, Van Hollen accused Trump of dishonesty about Greenland's national security value and said the president only cares about the territory's natural resources.
"The president is lying to the American people when he says this is about security," Van Hollen said.
