Donald Trump warned he no longer feels obliged to think "purely of peace" after being snubbed for a Nobel prize, in a message published on Monday, as the US president ramped up his campaign to take over Greenland.

In an extraordinary text message sent to Norway's prime minister, Trump questioned Denmark's rule over the vast Arctic island, which he said he wanted "complete and total control of".

The message came days after Trump threatened hefty new tariffs on European allies who oppose his plan, raising alarm in allied capitals and sending stock markets plummeting.

The US President told NBC News in a brief telephone interview that he would "100 percent" follow through on plans to impose tariffs on European nations with tariffs without a Greenland deal.

German and French leaders have denounced his threat as "blackmail".

Denmark meanwhile proposed that Nato start surveillance operations in Greenland to confront security concerns.

France said on Monday that Europe was preparing trade countermeasures – though US Treasury Secretary Scott Bessent, asked about potential retaliatory tariffs, warned: "I think it would be very unwise."

The European Union said it would hold an emergency summit on Thursday to weigh its response, and that while its priority was to "engage not escalate" it was ready to act if needed.

Greenland, for its part, said the tariff threat does not change its desire to assert its own sovereignty.

"We will not be pressured," Greenland's Prime Minister Jens-Frederik Nielsen said in a Facebook post, adding that the autonomous territory "is a democratic society with the right to make its own decisions".

In a message to Norway's Prime Minister Jonas Gahr Store, Trump said "I no longer feel an obligation to think purely of Peace", citing his failure to win last year's Nobel Peace Prize despite openly coveting it.

He said although peace would still be "predominant", he could "now think about what is good and proper for the United States of America".

Store said the statement had been received in response to a message from him and Finnish President Alexander Stubb, where they had "conveyed our opposition" to Trump's tariff threats.

"I have clearly explained, including to President Trump, what is well known – the prize is awarded by an independent Nobel Committee," not the Norwegian government, he said in a statement.

Bessent, speaking in response to a question at the World Economic Forum in Davos, Switzerland, dismissed any link between the Prize and Trump's plans for Greenland.

"I think it's a complete canard that the president will be doing this because of the Nobel Prize," he said.

Trump has repeatedly said his country needs vast, mineral-rich Greenland for "national security", despite the United States already having a base on the island and security agreements with fellow Nato ally Denmark.

"Denmark cannot protect that land from Russia or China," Trump said in his message to the Norwegian premier.

"Why do they have a 'right of ownership' anyway? There are no written documents, it's only that a boat landed there hundreds of years ago, but we had boats landing there, also," he said in his message to Store.

Denmark's Defence Minister Troels Lund Poulsen Monday met with Nato chief Mark Rutte to present a proposal for surveillance operations based in Greenland.

Rutte wrote on X that he had discussed "how important the Arctic – including Greenland – is to our collective security" with the Danish minister and Greenland's top diplomat.

"We'll continue to work together as Allies on these important issues," he wrote.

Meanwhile aircraft from North American Aerospace Defense Command (NORAD), a joint US-Canada military organisation, were announced to arrive "soon" at the US Pituffik Space Base in Greenland for "long planned" activities, the organisation said on Monday.

This weekend, Trump said that from February 1, Denmark, Norway, Sweden, France, Germany, the United Kingdom, the Netherlands, and Finland would be subject to a 10-percent tariff on all goods sent to the United States – a duty which could go higher.

Germany's vice chancellor Lars Klingbeil slammed the move as blackmail, and said on Monday that Europe was preparing countermeasures. (AFP/ Reuters)