A bipartisan group of US senators flew into Denmark on Friday – and straight into a fresh diplomatic standoff over Donald Trump’s aspirations to take over Greenland.

Even before the 11 visitors arrived, hoping to “reduce the temperature”, Denmark’s furious foreign minister Lars Løkke Rasmussen was threatening “a very, very short series of meetings”.

The reason for his fury was an overnight claim by White House press secretary Karoline Leavitt that the meeting – agreed between officials from the US, Denmark and Greenland on Wednesday – would discuss “the acquisition of Greenland”.

The US visitors were scheduled to meet both prime ministers of Denmark and Greenland, Mette Frederiksen and Jens-Frederik Nielsen. And to make an impression on the visitors, Denmark’s Folketinget parliament made sure to fly the red-and-white flag of the Arctic island – part of the Danish Kingdom of Denmark for three centuries.

Leading the US group was Democratic senator Chris Coons of Delaware, who said the visitors were there to listen to local views and “lower the temperature”.

Greenlandic politician Aaja Chemnitz Arnatsiaq Larsen, US senator Chris Coons and Danish politician Christian Friis Bach at the Danish parliament, Christiansborg, in Copenhagen on Friday. Photograph: Martin Sylvest Andersen/Getty ImagesGreenlandic politician Aaja Chemnitz Arnatsiaq Larsen, US senator Chris Coons and Danish politician Christian Friis Bach at the Danish parliament, Christiansborg, in Copenhagen on Friday. Photograph: Martin Sylvest Andersen/Getty Images

Republican senator Lisa Murkowski of Alaska said the Trump demand “was not a good idea” and promised to tell her US colleagues that “Greenland needs to be viewed as our ally, not as an asset”.

Back in the US, Trump threatened fresh tariffs on goods from countries that push back against his Greenland plan. “I may put a tariff on countries if they don’t go along with Greenland,” he said in the White House, “because we need Greenland for national security.”

Raising the temperature from a distance, too, was Jeff Landy. The governor of Louisiana and Trump’s special envoy for Greenland, who plans his first visit to the island in March, said Trump has “laid markers down” for a takeover. “I do believe that there’s a deal that should and will be made oncethis plays out,” he told Fox News.

Denmark-based Greenland MP Aaja Chemnitz attacked these interventions as proof that the Trump administration was “a difficult partner to have as you cannot count on what you have agreed”.

“This means that credibility is not very high, as I see it,” she said. “You can’t buy something that is not for sale. We have said that thousands of times in thousands of different ways.”

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After another week of megaphone – and closed-door – diplomacy, weekend marches are planned all over Denmark and Greenland in protest against Trump’s unwanted advances and demanding full self-determination for Greenland.

After 250 years as a Danish colony, Greenland has been moving towards self-rule since 1979 and, since 2009, has control over almost all competences except foreign and security affairs.

Demonstrations are planned at noon on Saturday in the Danish cities of Aarhus, Aalborg and Copenhagen, the last ending before the US embassy. The main organiser of the marches is the Inuit Joint Association, an umbrella organisation for groups representing Greenland’s native population. Chief organiser Camilla Siezing said the interest in the demonstration has been “huge”.

“Usually we don’t get involved in political issues,” said Siezing, “but with current the situation – and how it will affect Greenlandic heritage, identity and culture – we have found it difficult to hold back”.

Ahead of the weekend marches, one Danish flagmaker said demand for Greenlandic flag comprised “90 per cent of all our online orders this week, a sharp increase from the normal 3 to 5 per cent”.

The Greenlandic flag next to the main entrance of the Danish parliament, Christiansborg, in Copenhagen, Denmark. Photograph: Sebastian Elias Uth/Ritzau Scanpix/AFP via Getty ImagesThe Greenlandic flag next to the main entrance of the Danish parliament, Christiansborg, in Copenhagen, Denmark. Photograph: Sebastian Elias Uth/Ritzau Scanpix/AFP via Getty Images

In Greenland’s capital Nuuk, a rally on Saturday at 1pm will march to the US consulate.

Organiser Bikki Jepsen said the main message of marchers was for the US to respect Greenland’s democracy, its right to self-determination and fundamental human rights.

Organiser, Avijaja Rosing-Olsen, said Greenland’s demand for self-determination and respect was not just a local issue: “This is a struggle that concerns the whole world.”