Denmark's Prime Minister Mette Frederiksen says "Europe won't be blackmailed", as she and other European leaders continue to weigh their response to US President Donald Trump's tariff threats over Greenland.

Trump says he will impose new taxes on eight US allies - Denmark, Finland, France, Germany, the Netherlands, Norway, Sweden and the UK - in February if they oppose his proposed takeover of the autonomous Danish territory.

He insists Greenland is critical for US security and has not ruled out taking it by force - a move that has drawn widespread criticism.

The countries threatened with tariffs have now issued a joint statement, saying Trump's plan risks a "dangerous downward spiral".

"Tariff threats undermine transatlantic relations," they said, reiterating that they "stand in full solidarity with the Kingdom of Denmark and the people of Greenland".

The countries stressed they are "committed to strengthening Arctic security as a shared transatlantic interest" as members of the Nato military alliance.

"We stand ready to engage in a dialogue based on the principles of sovereignty and territorial integrity that we stand firmly behind," the statement reads.

Separately, Frederiksen wrote on Facebook: "We want to cooperate and we are not the ones seeking conflict. And I am happy for the consistent messages from the rest of the continent: Europe will not be blackmailed."

"It is all the more important that we stand firm on the fundamental values that created the European community."

Meanwhile, UK Prime Minister Sir Keir Starmer said he had had phone calls on Sunday with Frederiksen, as well as European Commission President Ursula von der Leyen and Nato Secretary-General Mark Rutte, before speaking to Trump.

A spokeswoman for Starmer's office said he had reiterated his position that Greenland's security was a priority for all Nato members. "He also said that applying tariffs on allies for pursuing the collective security of Nato allies is wrong," the spokeswoman added.

Trump has threatened to impose a 10% tariff on goods from Denmark, Norway, Sweden, France, Germany, the UK, the Netherlands and Finland, which would come into force on 1 February, but could later rise to 25% - and would last until a deal was reached.

"These Countries, who are playing this very dangerous game, have put a level of risk in play that is not tenable or sustainable," he wrote, adding: "This is a very dangerous situation for the Safety, Security and Survival of our Planet".

The US president insists Greenland is critical for US security and has said previously that Washington would get the territory "the easy way" or "the hard way".

Greenland is a sparsely populated but resource-rich area, and its location between North America and the Arctic makes it well placed for early warning systems in the event of missile attacks and for monitoring vessels in the region.

US Treasury Secretary Scott Bessent on Sunday told NBC News' Meet the Press that "Greenland can only be defended if it is part of the US, and it will not need to be defended if it is part of the US".

"I believe that the Europeans will understand that this is best for Greenland, best for Europe and best for the United States," he said.

Speaking to BBC Newshour, Norwegian Foreign Minister Espen Barth Eide said mutual respect for sovereignty is the "non-negotiable" core principle of international law and co-operation.

"If we are to live in peace and if we are to be able to co-operate on shared problems, we have to start by the mutual recognition of each other's sovereignty and territorial integrity," she added.

It is still unclear how the tariffs will affect those Trump has already imposed on the UK and EU. French President Emmanuel Macron, who is working to co-ordinate the European response to the tariff threats, said he would request that the EU activate its "anti-coercion instrument" if Trump does impose them.

The US president is due to speak at the World Economic Forum in Davos, Switzerland on Wednesday on the theme "how can we co-operate in a more contested world?" Macron, as well as the leaders of Germany and the EU, will also be attending the annual conference.

Canadian Prime Minister Mark Carney, who will also be there, said his country was "concerned by the recent escalation" and that it would be "significantly increasing Arctic security — strengthening our military and investing in critical infrastructure".

"Canada strongly believes that the best way to secure the Arctic is by working together within Nato," he also wrote on X.

Mark Rutte, meanwhile, said he had spoken to Trump "regarding the security situation in Greenland and the Arctic".

"We will continue working on this, and I look forward to seeing him in Davos later this week," he added.

Public anger in both Denmark and Greenland over Trump's threats to buy Greenland appears undiminished. Demonstrations against Trump's takeover plans were held in Greenland's capital, Nuuk, on Saturday - before the tariff announcement - as well as in Danish cities.

These rallies coincide with a visit to Copenhagen by a US Congressional delegation. Its leader, Democratic Senator Chris Coons, described Mr Trump's rhetoric as "not constructive".

The island's representative to the US has said that the last time Greenlanders were asked whether they wanted to be part of the US, in January 2025, only 6% were in favour, while 85% were against.

A recent poll suggests that most Americans also oppose US control of Greenland. A Reuters/Ipsos poll released last Wednesday found that just 17% of Americans support the US taking Greenland, compared with 47% who oppose Trump's push to acquire the island.