He said that the US will “have the complete ability to do what is necessary in Greenland in order to secure and defend the security of Greenland, and the United States of America” in a post on Truth Social.
Mr Trump added that the US would soon deploy a large military presence on the island without offering further details.
But what does the new deal actually entail and how will it be implemented? Sky News explains.
What does the agreement cover?
A State Department official told Reuters that the deal prohibits non-NATO countries from building a base in Greenland.
They added that only the US and its allies will be able to make “sensitive investments” – though the nature of these investments is currently unclear.
The US will also be granted permanent access, basing and overflight rights, the official added.
All of these conditions will reportedly continue to apply even if Greenland becomes independent.
Mr Trump’s Truth Social posts lacked specifics and much remains unclear, including whether new US bases may be constructed as a result of the agreement.
Imran Bayoumi, a former Pentagon official now with the Atlantic Council think tank, said that Washington “could have achieved a lot of these objectives through diplomacy and dialogue without straining the broader US-NATO relationship”.
Parliamentary action by the Danish and Greenland governments will also be required before the deal can be enforced.
How have Denmark and Greenland reacted?
Denmark’s prime minister Mette Frederiksen confirmed the news on Friday evening and said the deal is expected to be signed next week.
She said “there is a prospect of a good agreement for Greenland, the kingdom of Denmark and the US”.
Ms Frederiksen called it “an agreement that strengthens our common security in the Arctic and the North Atlantic area”.
Greenland’s prime minister Jens-Frederik Nielsen also said it would “ensure and strengthen” the security of Greenland, Denmark, the US, and the Western alliance – calling it “to the benefit of us all”.
Why is Greenland strategically important?
Greenland, which is northeast of Canada, is a semi-autonomous territory of Denmark.
The island of just 57,000 people offers a unique geopolitical advantage which the US has coveted for more than 150 years.
Mr Trump has repeatedly made his ambition to own Greenland known and even made implicit threats of military action.
He previously said it is “very important for the national security of the United States, Europe, and other parts of the free world”.
The shortest distance between Russia and the US is over Greenland, making it a critical site for the US ballistic missile defence system.
It is already home to a large US military base, called the Pituffik Space Base.
Sky News’ military analyst Sean Bell previously said that global warming is melting Greenland’s ice sheet and opening up new trade routes that have historically been frozen and impassable for most of the year.
New, cheaper routes for shipping goods from Europe to Japan are consequently opening around Greenland.
Is there really a national security threat in Greenland?
Mr Trump has repeatedly suggested there are immediate threats to the US and NATO countries in Greenland.
Sky’s US correspondent James Matthews said that conversations over the territory had centred around US security concerns.
He said: “Discussions focused on Greenland territory being used for the golden dome – the defence shield to guard against missiles being fired over the Arctic region from the likes, potentially, of China and Russia.”
However, experts have challenged Mr Trump’s claims that Russian and Chinese ships are posing a threat around Greenland.
Read more from Sky News:
‘Millisecond’ software error caused air traffic outage
All government departments to refresh war plans
Peter Viggo Jakobsen, an associate professor at the Royal Danish Defence College, previously told Sky News: “There is no acute problem to solve – the Chinese and Russian ships that he keeps talking about are a figment of his imagination.
“There is no security threat to Greenland,” he added, explaining that China does not operate warships and submarines in the Arctic and that while Russia may operate the odd submarine near Greenland on occasion, “that is it”.
The US military already has de facto military control of Greenland, as it has since the Second World War.
