WASHINGTON / COPENHAGEN (Sept. 18, 2026) — The United States and Denmark announced a security agreement covering Greenland on Friday, with President Donald Trump claiming the pact gives Washington “permanent control over security, and all other needs” on the Arctic island — and Danish Prime Minister Mette Frederiksen saying the deal will be signed next week at the United Nations General Assembly.

In a Truth Social post Friday evening (~5:18 p.m. ET), Trump said the United States had “entered into an Agreement with The Kingdom of Denmark, and Greenland,” that “completely address[es] ALL of our many U.S. concerns,” comes with “NO COST to the United States,” and guarantees America the ability to “do what is necessary” to “secure and defend the security of Greenland, and the United States of America.”

…gives the United States permanent control over security, and all other needs, in Greenland… There will be NO COST to the United States! … the United States will FOREVER have the complete ability to do what is necessary in Greenland in order to secure and defend the security of Greenland… Additionally, from now on, no U.S. adversary can EVER have a base in Greenland, have a military presence in Greenland, or make sensitive investments in Greenland, without our express written approval.

— Donald J. Trump on Truth Social, Sept. 18, 2026

BBC News and NewsNation (via The Hill) confirmed the announcement Friday. Frederiksen said the agreement “strengthens our common security in the Arctic and the North Atlantic area” while it “at the same time recognizes the sovereignty and territorial integrity of the Kingdom and the right of the Greenlandic people to self-determination,” the BBC reported. She confirmed signing at UNGA next week.

NewsNation reported a joint Greenland–Denmark statement that the agreement is expected to be signed during the high-level UNGA summit next week, and that Greenland’s and Denmark’s parliaments will also have to approve it. Greenland Prime Minister Jens-Frederik Nielsen called it gratifying to enter an agreement that “ensures and strengthens the security of Greenland, the Kingdom of Denmark, the United States and the Western alliance.”

Rubio: “historic deal”

U.S. Secretary of State Marco Rubio called it a “historic deal” and a “huge win for the United States and the American people.” “This deal permanently and completely addresses our national security concerns in Greenland,” he told Fox News, according to the BBC.

Trump also said the United States would “immediately begin the process of developing a large Military presence in the appropriate part of Greenland” and work with Greenlanders on development and construction — language that goes beyond a narrow basing update and into a long-horizon security writ over a self-governing territory that Denmark still insists remains under Kingdom sovereignty.

Security pact vs. sovereignty — the tension

The deal lands after months of Trump threats to “take” Greenland over national-security and mineral concerns. What was announced Friday is a security arrangement, not a transfer of title — Frederiksen’s framing explicitly pairs Arctic defense with recognition of Kingdom sovereignty and Greenlandic self-determination. Whether “permanent control over security, and all other needs” can coexist with that sovereignty claim is the political and legal question the UNGA signing and parliamentary votes will test. Empire by pact still has to clear allied legislatures.

Dated Friday, Sept. 18, 2026: US–Denmark–Greenland security deal announced; UNGA signing next week per Frederiksen; Trump Truth Social “permanent control” / “no cost” / adversary veto; Rubio “historic deal.”

Sources