What happened
Greenland is an autonomous territory of Denmark, a NATO member since the alliance's founding in 1949 — meaning a US attack on Greenland would, on paper, trigger the same mutual-defence obligations the US relies on to defend every other ally in Europe. Trump's team nonetheless confirmed active internal discussion of an acquisition offer, and when directly asked whether military force was on the table, Trump would not rule it out, separately threatening a 25% import tariff on goods from several European countries specifically to pressure Denmark into ceding the territory.
Danish Prime Minister Mette Frederiksen's response was blunt: if the US attacked a NATO ally militarily, "then everything stops... including our NATO and thus the security that has been provided since the end of the Second World War" — a warning that the alliance's central bargain could not survive a member being invaded by its own supposed protector. Denmark's Defence Intelligence Service, in its 2025 threat assessment, named the United States as a national security concern for the first time in its history, in the same document as Russia and China.
A joint letter from European leaders stated plainly that "Greenland belongs to its people" and that its status was a matter for Denmark and Greenland alone. Trump later walked the threat back at the 2026 Davos conference, pledging not to use force or tariffs to annex the territory — but the earlier threats had already been made publicly, repeatedly, and were taken seriously enough by a NATO ally's government to reshape its own threat assessment.