Burnham and Danish Prime Minister Mette Frederiksen "welcomed the US's commitment to the region" in a phone call on Sunday, according to a No. 10 spokesperson. The two leaders "underlined the strategic and shared importance of the High North for Euro-Atlantic security."
The UK premier's comments come as he is expected to meet Trump at the UN General Assembly in New York this week. The deal itself is expected to be signed at the same gathering.
No text of the agreement has been released, but Trump posted on Truth Social that Denmark would grant the US "permanent control over security, and all other needs" in Greenland, the world's largest island and a semiautonomous Danish territory. He said the deal came with "no cost to the United States" and would allow Washington "to do what is necessary" to "secure and defend the security of Greenland."
Trump added that the agreement includes a rule barring any US adversary from maintaining a military presence in Greenland or making "sensitive investments" without US approval.
A Nato spokesperson said the alliance welcomed the accord, which would "help advance security, stability and cooperation in this vital region."
Frederiksen said she was "pleased that there is a prospect of a good agreement" for all three parties—Denmark, Greenland, and the United States. Greenland's leaders also welcomed the deal to "strengthen security," though neither Danish nor Greenlandic officials outlined its specific contents.
The deal follows months of escalating tension after Trump repeatedly threatened to "take" Greenland, citing its strategic Arctic location for defence and its mineral wealth. The New York Times notes it remains unclear how the new agreement will differ from a 1951 U.S.-Denmark defense pact that already allows Washington to operate bases on the island. Foreign Policy has questioned what the arrangement will mean for NATO's role in the region.