Copenhagen, Denmark - Denmark said Monday it would summon the US ambassador after President Donald Trump provocatively appointed a special envoy to Greenland, the Danish autonomous territory he has threatened to annex.

Since returning to the White House in January 2025, Trump has repeatedly said the US claimed the resource-rich island for "security" reasons, and has refused to rule out the use of force to secure it.

On Sunday, he further inflamed tensions by appointing Louisiana Governor Jeff Landry as special envoy to Greenland.

Danish Foreign Minister Lars Lokke Rasmussen said Monday he was "deeply angered" by the move and warned Washington to respect Denmark's sovereignty.

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In a Truth Social post, Trump said Landry "understands how essential Greenland is to our National Security, and will strongly advance our Country's Interests for the Safety, Security, and Survival of our Allies, and indeed, the World."

Landry responded directly to Trump in a post on X: "It's an honor to serve you in this volunteer position to make Greenland a part of the US."

The Danish foreign minister told television TV2 the appointment and statements were "totally unacceptable" and said his ministry would call in the US ambassador in the coming days "to get an explanation".

"As long as we have a kingdom in Denmark that consists of Denmark, the Faroe Islands, and Greenland, we cannot accept that there are those who undermine our sovereignty," he said.

Greenland's Prime Minister Jens-Frederik Nielsen, meanwhile, said the appointment "doesn't change anything for us here at home".

"We will determine our future ourselves. Greenland is our country," he wrote on Facebook, adding: "Greenland belongs to Greenlanders, and territorial integrity must be respected."

The vast majority of Greenland's 57,000 people want to become independent from Denmark, but do not wish to become part of the US, according to a January opinion poll.

Leaders of both Denmark and Greenland have repeatedly insisted that the huge Arctic island is not for sale and that it will decide its future itself.

In August, Denmark summoned the US chargé d'affaires after reports of attempted interference in Greenland.

At least three officials close to Trump were observed in Greenland's capital Nuuk trying to identify people for and against US annexation.