TL;DR: U.S. claims permanent security control in Greenland, will expand military and space footprint while Denmark keeps sovereignty.

President Donald Trump announced on Friday, Sept. 18, 2026, that the United States has entered into an agreement with the Kingdom of Denmark and Greenland that gives the United States permanent control over security and all other needs in Greenland, a move centered on expanded military basing, overflight rights and space-domain operations anchored by Pituffik Space Base in northwestern Greenland. The text of the agreement has not been released, and leaders in Copenhagen and Nuuk said the pact is expected to be signed next week in connection with the United Nations General Assembly in New York City, after which parliamentary procedures would still be required before it can enter into force, according to NBC News.

The announcement reframes months of U.S. pressure to take over the semiautonomous Danish territory into a security and basing arrangement that leaves sovereignty and territorial integrity with the Kingdom of Denmark and preserves the Greenlandic people's right to self-determination, according to the BBC. For U.S. space and defense planners, the practical effect described by U.S. officials is permanent access, basing and overflight rights in Greenland, authority to add bases as required, exclusion of adversary bases and investment screening aimed at Russia and China.

What Trump announced on Sept. 18

Truth Social declaration and "Infinite Life" label

Trump said in a post on Truth Social on Sept. 18 that he was pleased to announce that the United States of America has entered into an Agreement with the Kingdom of Denmark, and Greenland, that gives the United States permanent control over security, and all other needs, in Greenland, completely addressing all U.S. concerns, according to NBC News. Trump described the arrangement as an Infinite Life agreement and said it would come at no cost to the United States, according to NBC News.

Trump also said the agreement would grant the United States the ability to do what is necessary to secure and defend the security of Greenland, according to the BBC. He said the administration will work with Greenland to immediately begin developing a large military presence in the appropriate part of Greenland, of which there are many, according to NBC News.

Trump said the deal included a rule that no U.S. adversary could maintain a military presence in Greenland or make sensitive investments in Greenland without U.S. express written approval, according to the BBC. Reporting by Reuters on Sept. 18 summarized the same central claim, that Washington has entered into an agreement with Denmark and Greenland that gives the U.S. permanent control over security, and all other needs, in Greenland.

What U.S. officials say is in the unpublished text

The full text of the agreement has not been released, but a State Department official outlined provisions to news organizations without providing specifics, according to the BBC. The official said the deal would not expire even if Greenland became an independent country in the future, according to the BBC.

The same official said the United States has unilateral power to build additional military structures with no approval needed from Greenland or Denmark, and that the pact includes permanent access, basing and overflight rights, according to the BBC. A State Department official told NBC News that the agreement explicitly guarantees the United States the complete ability to do what it deems is necessary in Greenland in order to secure and defend the American continent, including permanent access, basing, and overflight rights.

The agreement explicitly bans any non-NATO base or troop presence in Greenland, and it includes screening mechanisms intended to block investments from Russia and China and bans them, and other adversaries, from making investments in Greenland that could threaten the U.S., according to NBC News. The official specifically referenced Russia and China, saying the arrangement blocks them from deploying troops or making investments in sensitive sectors, according to the BBC. The official added that under the current status quo, adversaries have been allowed to invest in Greenland's sensitive sectors without investment screening, according to the BBC.

Secretary of State Marco Rubio said Greenland will forever be part of the strategic defense area of North America and exclude any adversary from it and the surrounding area, according to NBC News. Rubio said the deal permanently and completely addresses U.S. national security concerns in Greenland, according to NBC News.

Why Pituffik Space Base is central to the deal

Missile warning, missile defense and space surveillance

The United States already has a military base on Greenland and rights to expand its presence there through existing agreements dating back to 1951, according to NBC News. The American military presence on Greenland has been significantly scaled back since the height of the Cold War, when critical missile early-warning systems were installed there, according to NBC News.

During the first Trump administration, the former U.S. Air Force base was handed over to the newly created Space Force and re-designated as Pituffik Space Base, according to NBC News. The base supports missile warning, missile defense and space surveillance operations for the U.S. and NATO, according to reporting associated with The Associated Press and carried in the Sept. 19 ABC News account of the Sept. 18 announcement.

The United States already has more than 100 military personnel permanently stationed at its Greenland installation, according to the BBC. Without the official text being released, it is unclear how exactly the new deal differs from the 1951 agreement with Denmark, under which the U.S. can send as many troops as it wants to Greenland, according to the BBC.

U.S. officials frame the new language as ensuring the necessary U.S. military presence in Greenland permanently, allowing the U.S. military to increase the number of bases in Greenland as required, according to NBC News. A U.S. State Department official told NBC News that the agreement will remain fully in effect forever, including if Greenland becomes a fully independent country from Denmark.

Air defense geography and Arctic sea routes

Greenland's location between North America and the Arctic makes it well placed for early warning systems for missile attacks, and for monitoring vessels, according to the BBC. PBS News reported on Sept. 18 that Greenland is the shortest distance between Russia and the United States, so very key for air defense.

PBS News also reported that Russian and Chinese ships have used routes around Greenland that have been opening up because of warming climate, a factor cited among the national security concerns behind U.S. interest. The same report said Trump has viewed Greenland as an investment venue and sought to secure American investment rights, rather than Chinese and Russian investment rights, for critical minerals.

Only around 56,000 people live in Greenland, which was colonized by Denmark and Norway more than 300 years ago, according to NBC News. The island is about three times the size of Texas, but it appears much larger on the traditional Mercator projection world map because its scale is distorted, according to NBC News. Greenland contains vast mineral resources, much of which remain untapped due to its hostile climate, according to NBC News.

Sovereignty stays with Denmark as signing is planned

Copenhagen and Nuuk statements

The island will remain part of Denmark under the new deal, Danish Prime Minister Mette Frederiksen indicated Friday in a statement alongside Greenland's leaders, short of Trump's previous demand, according to NBC News. Frederiksen said the agreement recognizes Danish sovereignty and territorial integrity as well as Greenlanders' right to self-determination, according to NBC News.

The deal strengthens common security in the Arctic and the North Atlantic area while also recognising the sovereignty and territorial integrity of the Kingdom and the right of the Greenlandic people to self-determination, Frederiksen said in a joint statement with Greenland Prime Minister Jens-Frederik Nielsen, according to the BBC. Frederiksen said she was pleased that there is a prospect of a good agreement for all three parties, which was expected to be signed at the U.N. General Assembly next week, according to the BBC.

Nielsen said it was gratifying that the parties are about to enter into an agreement that ensures and strengthens the security of Greenland, the Kingdom of Denmark, the United States and the Western alliance, according to the BBC. Nielsen said the agreement recognizes Greenland's interests and place in international cooperation and is for the benefit of all, according to the BBC. In a separate statement cited by NBC News, Nielsen wrote that the deal is to the benefit of us all.

The agreement is expected to be signed by Denmark, Greenland and the U.S. next week in connection with the upcoming United Nations General Assembly in New York City, Denmark said, according to NBC News. The agreement would still need to go through the necessary parliamentary procedures to enter into force once signed, according to the BBC.

NATO and allied reaction

A NATO spokesperson said the military alliance welcomed the deal, which would help advance security, stability and cooperation in this vital region, according to the BBC. Frederiksen described the deal as an agreement that strengthens common security in the Arctic and the North Atlantic area and is therefore also good for NATO and Europe, according to NBC News.

French President Emmanuel Macron said the deal helped to reaffirm Danish sovereignty over the island, according to the BBC. Macron said Danish sovereignty is respected, international law is respected, and that this is what had been requested, according to reporting by Agence France-Presse cited by the BBC.

PBS News reported on Sept. 18 that U.S. and European officials contacted that day both appeared satisfied, with permanent U.S. basing, access and overflight rights on one side and no transfer of Greenland territory to the United States on the other. PBS News reported that the Greenland population can choose its political future, including a possible choice for independence, and that no territory of Greenland is transferred to the United States under the arrangement described by officials.

From takeover threats to a basing agreement

Trump has previously rattled Europe with demands for the U.S. to take over the territory, a semiautonomous region of NATO member Denmark, on occasion threatening military action and vowing to take control one way or the other, according to NBC News. Those threats led to warnings that such a move could effectively collapse the U.S.-led NATO alliance, according to NBC News.

Trump had tried for months to purchase or annex the semiautonomous territory, arguing that it was vulnerable to adversaries, including Russia and China, according to the BBC. His repeated demands to take Greenland earlier this year prompted an outcry from Greenlanders, Danes and other NATO members, according to the BBC. The leader had argued that the U.S. must take control of Greenland to avoid Russia and China gaining influence in the Arctic territory, an argument Beijing dismissed as an excuse to pursue territorial ambitions, according to NBC News.

Greenlanders protested against Trump's ambitions for the territory in the capital, Nuuk, earlier this year, according to the BBC. Trump's previous approach has sparked outrage from Greenlanders, who consistently have shown in polls that they overwhelmingly reject American annexation, according to NBC News.

U.S. Vice President JD Vance toured a U.S. military base in Greenland earlier this year, in a visit viewed by Copenhagen and Nuuk as a provocation amid Trump's demands, according to the BBC. The Trump administration continued efforts to sway opinion, including with a visit from the U.S. special envoy to Greenland, Louisiana Gov. Jeff Landry, in May, according to NBC News. Despite opposition to Trump's threats, Greenland's government had been participating in negotiations alongside Denmark and the U.S. to find a solution to security concerns, according to NBC News.

Sources referenced