"We are open to criticisms, but let me be completely honest, we do not appreciate the tone in which it's being delivered," Foreign Minister Lars Lokke Rasmussen said on X.

"This is not how you speak to your close allies, and I still consider Denmark and the United States to be close allies," he said.

Vance made his comments during a trip to the Pituffik Space Base in northwestern Greenland, viewed by both Copenhagen and Nuuk as a provocation.

"Our message to Denmark is very simple: You have not done a good job by the people of Greenland," Vance told a press conference.

"You have under-invested in the people of Greenland and you have under-invested in the security architecture of this incredible, beautiful landmass," he added.

Trump argues that the United States needs the vast Arctic island for national and international security and has refused to rule out the use of force to secure it.

"We are not talking about peace for the United States. We are talking about world peace. We are talking about international security," Trump claimed to reporters at the White House on Friday.

Asked about the potential use of force, Vance stressed the US administration did not think that "is ever going to be necessary".

"We think this makes sense and because we think the people of Greenland are rational and good, we think we're going to be able to cut a deal, Donald Trump-style, to ensure the security of this territory but also the United States of America," Vance said.

Denmark's Prime Minister Mette Frederiksen also hit back at Vance in a statement.

"For many years, we have stood by the Americans in very difficult situations," she said, referring to Danish combat deployments alongside American troops in Iraq and Afghanistan.

"The Vice President's reference to Denmark is not accurate," she said.

Vance was accompanied by his wife Usha, National Security Advisor Mike Waltz, Energy Secretary Chris Wright, Utah Senator Mike Lee and former Homeland Security Advisor Julia Nesheiwat, who is Waltz's wife.

- 'Unacceptable pressure' -

Danish and Greenlandic officials, backed by the European Union, have insisted that the United States will not obtain Greenland.

Frederiksen has condemned the US decision to visit the Arctic island uninvited as "unacceptable pressure" on Greenland and Denmark.

A majority of Greenlanders opposes US annexation, according to a January poll.

The Pituffik base is an essential part of Washington's missile defence infrastructure, its location in the Arctic putting it on the shortest route for missiles fired from Russia at the United States.

Known as Thule Air Base until 2023, it served as a warning post for possible attacks from the Soviet Union during the Cold War.

It is also a strategic location for air and submarine surveillance.

In January, Copenhagen said it would allocate almost two billion dollars to beef up its presence in the Arctic and north Atlantic, acquiring specialised vessels and surveillance equipment.

Greenland is home to 57,000 people, most of them Inuits.

It is believed to hold massive untapped mineral and oil reserves, although oil and uranium exploration are banned.

Trump's desire to take over the territory has been categorically rejected by Greenlanders, their politicians and Danish officials.

- Unity call -

While all of Greenland's political parties are in favour of independence, none of them supports the idea of becoming part of the United States.

A new broad four-party coalition government was announced in Greenland just hours before the US delegation's arrival, following elections earlier this month.

Incoming prime minister Jens-Frederik Nielsen said the territory needed unity at this time.

"It is very important that we put aside our disagreements and differences... because only in this way will we be able to cope with the heavy pressure we are exposed to from outside," he said.