The US is set to significantly expand its military presence in Greenland under a new security agreement with Denmark, President Donald Trump has announced.

Speaking at the UN General Assembly in New York on Tuesday, Trump revealed details of the deal, which is due to be formally signed following his address.

“We will have the complete ability to do what is necessary to defend the American continent, and also Europe and other places,” Trump said. “No US adversary will ever be permitted to establish a military presence in Greenland any more, or make sensitive investments there without our express written approval.”

Trump later signed the agreement with Danish Prime Minister Mette Frederiksen and Greenlandic Prime Minister Jens-Frederik Nielsen on the sidelines of the UN gathering.

The planned US expansion is expected to include Narsarsuaq in southern Greenland, the site of the former American Bluie West One airbase, and Mestersvig on the east coast, a military outpost currently used by Denmark’s Sirius Dog Sled Patrol, Reuters reported, citing people familiar with the agreement.

Greenland, the world’s largest island, is a self-governing territory within the Kingdom of Denmark. Its location between the Arctic and North Atlantic has long made it strategically important for regional security and military operations.

The US already operates Pituffik Space Base in northwestern Greenland, formerly known as Thule Air Base. The Pentagon’s northernmost installation supports missile warning, missile defense, and space surveillance operations.

Washington has maintained a military presence in Greenland since World War II. A 1951 agreement with Denmark provided the legal basis for US operations there. The American presence was much larger during the Cold War before being reduced to the single base at Pituffik.

The new agreement follows months of tensions over Greenland that strained relations between the US and its European allies. Trump repeatedly pushed for American control of the island and refused to rule out taking it by military force, prompting Denmark and Greenland to insist that the territory was not for sale and that its future could only be decided by Greenlanders.