Denmark's prime minister, Mette Frederiksen, says her country faces a "decisive moment" in its diplomatic battle with the United States over Greenland, after President Donald Trump again suggested using force to seize the Arctic territory.

Ms Frederiksen said that "there is a conflict over Greenland", in a debate with other Danish political leaders.

"This is a decisive moment,"

she said.

Ms Frederiksen also posted on Facebook that "we are ready to defend our values — wherever it is necessary — also in the Arctic. We believe in international law and in peoples' right to self-determination".

Polls indicate that Greenland's population strongly opposes a US takeover. (Reuters: Guglielmo Mangiapane)

Mr Trump has said controlling Greenland was crucial for US national security because of the rising Russian and Chinese military activity in the Arctic.

He has repeated that Washington was "going to do something on Greenland, whether they like it or not".

This feud comes ahead of a week of meetings in Washington on the global scramble for key raw materials, which US and EU representatives will attend.

US Vice-President JD Vance toured the US military's Pituffik Space Base in Greenland in March last year. (Pool: Jim Watson via Reuters)

Greenland was a Danish colony until 1953, when it was fully integrated into the Kingdom of Denmark.

It is contemplating eventually loosening its ties with Denmark, but polls indicate that Greenland's population strongly opposes a US takeover.

European countries support Denmark

Last week, leaders of seven European countries, including France, Britain, Germany and Italy, signed a letter saying it is "only" for Denmark and Greenland to decide the territory's future.

Sweden and Germany also independently voiced their support for Denmark.

Swedish Prime Minister Ulf Kristersson condemned the US's "threatening rhetoric".

Ulf Kristersson says Sweden "stands together" with Denmark. (AP Photo: Jean-Francois Badias)

"Sweden, the Nordic countries, the Baltic states, and several major European countries stand together with our Danish friends," he told a defence conference in Salen, where the US general in charge of NATO took part.

Mr Kristersson said a US takeover of mineral-rich Greenland would be "a violation of international law and risks encouraging other countries to act in exactly the same way".

Germany also reiterated its support for Denmark and Greenland.

Before meeting US counterpart Marco Rubio on Monday, German Foreign Minister Johann Wadephul held talks in Iceland to address the "strategic challenges of the Far North", according to a foreign ministry statement.

Greenland was a Danish colony until 1953 when it became fully integrated into the Kingdom of Denmark and gained representation in their parliament. (Reuters)

"Security in the Arctic is becoming more and more important" and "is part of our common interest in NATO", he said at a joint news conference with Icelandic Foreign Minister Thorgerdur Katrin Gunnarsdottir.

"If the American president is looking at what threats might come from Russian or Chinese ships or submarines in the region, we can of course find answers to that together," he added.

But "the future of Greenland must be decided by the people of Greenland" and Denmark, he said.

Asked about a possible strengthening of NATO's commitment in the Arctic, Mr Wadephul said Germany was "ready to assume greater responsibilities".

Earlier on Sunday, German Finance Minister Lars Klingbeil said:

"We are strengthening security in the Arctic together, as NATO allies, and not against one another."

US says there is 'no immediate threat'

Head of the US European Command, General Alexus Grynkewich, told the Swedish conference that alliance members were discussing Greenland's status.

While there was no immediate threat to NATO territory, the Arctic's strategic importance was growing fast, the US general said.

General Alexus Grynkewich says talks on Greenland are being held at the North Atlantic Council. (Reuters: Omar Havana)

"I don't think there's an immediate threat to NATO territory right now," General Grynkewich told the conference.

But he said Russian and Chinese vessels had been seen patrolling together on Russia's northern coast and near Alaska and Canada, working together to get greater access to the Arctic as ice recedes due to global warming.

General Grynkewich said he would not comment on "the political dimensions of recent rhetoric", but talks on Greenland were being held at the North Atlantic Council.

"Those dialogues continue in Brussels. They have been healthy dialogues from what I've heard," he said.

AFP