Vance made his comment during a trip to the Pituffik Space Base in northwestern Greenland, a visit viewed by 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 hit back at Vance in a statement to Danish media.

"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, expressing her readiness to "cooperate day and night with the Americans" on Arctic security.

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.

The US delegation boarded Air Force Two to leave Greenland just before 4:00 pm (1800 GMT), with the Vances waving at the top of the aircraft stairs.

- '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 -- for what was initially a broader visit to Greenlandic society -- 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 the northern hemisphere.

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.

Russian President Vladimir Putin said on Thursday he considered Trump's plans for Greenland "serious".

He voiced concern that "NATO countries, in general, are increasingly designating the far north as a springboard for possible conflicts".

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.

- 'Not showing respect' -

US Energy Secretary Chris Wright, a former mining executive, told Fox News on Thursday that he hoped the United States and Greenland could cooperate on mining to "bring jobs and economic opportunity to Greenland and critical minerals and resources to the United States".

Trump's desire to take over the ice-covered territory, which is seeking independence from Denmark, has been categorically rejected by Greenlanders, their politicians and Danish officials.

While all of Greenland's political parties are in favour of independence, none of them support 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 when he unveiled his government.

Nielsen said that by visiting Greenland when there was no government in office there, the US administration was "not showing respect to an ally".

Usha Vance had initially been due to travel to Greenland just with her son and attend a dogsled race in the town of Sisimiut.

Locals said they had planned to give her a frosty reception, with several protests scheduled.

The visit to Sisimiut was then cancelled and replaced with the visit to the military base.