US President Donald Trump has been discussing "a range of options" to acquire Greenland, including use of the military, the White House said,
BBC reports.
The White House told the BBC that acquiring Greenland - a semi-autonomous region of fellow Nato member Denmark – was a "national security priority".
The statement came hours after European leaders issued a joint statement rallying behind Denmark, which has been pushing back against Trump's ambitions for the Arctic island.
Trump repeated over the weekend that the US "needed" Greenland for security reasons, prompting Danish Prime Minister Mette Frederiksen to warn that any attack by the US would spell the end of Nato.
The White House said on Tuesday: "The president and his team are discussing a range of options to pursue this important foreign policy goal, and of course, utilizing the US military is always an option at the Commander-in-Chief's disposal."
Nato is a trans-Atlantic military group where allies are expected to go to each other's aid in case of external attacks.
On Tuesday, six European allies expressed support for Denmark.
"Greenland belongs to its people, and only Denmark and Greenland can decide on matters concerning their relations," the leaders of the UK, France, Germany, Italy, Poland, Spain, and Denmark said in a joint statement.
Stressing they were as keen as the US in Arctic security, the European signatories of the joint statement said this must be achieved by Nato allies, including the US "collectively".
They also called for "upholding the principles of the UN Charter, including sovereignty, territorial integrity and the inviolability of borders".
Greenland's Prime Minister Jens-Frederik Nielsen welcomed the statement and called for "respectful dialogue".
"The dialogue must take place with respect for the fact that Greenland's status is rooted in international law and the principle of territorial integrity," Nielsen said.
The issue of Greenland's future resurfaced in the wake of the US military intervention in Venezuela, during which elite troops seized the country's President Nicolás Maduro and took him to face drugs and weapons charges in New York.
A day after that raid, Katie Miller - the wife of one of Trump's senior aides - posted a map on social media of Greenland in the colours of the American flag, alongside the word "SOON".
On Monday, her husband, Stephen Miller, said it was "the formal position of the US government that Greenland should be part of the US".
Asked repeatedly in an interview with CNN whether America would rule out using force to annex it, Miller responded: "Nobody's going to fight the US over the future of Greenland."
