President Donald Trump signed a trilateral security agreement with Denmark and Greenland on Tuesday on the sidelines of the United Nations General Assembly in New York, paving the way for a significantly expanded U.S. military presence on the strategically important Arctic island. The agreement was signed alongside Danish Prime Minister Mette Frederiksen and Greenlandic Prime Minister Jens-Frederik Nielsen after months of negotiations aimed at addressing U.S. security concerns while preserving Greenland’s status under Danish sovereignty.

Under the agreement, the United States will be allowed to modernize and expand operations at Pituffik Space Base and establish additional defense areas at Narsarsuaq in southern Greenland and Mestersvig on the eastern coast. The agreement also permits the creation of additional U.S. defense areas in Greenland, subject to consultations and mutual agreement among the parties.

Trump said in his UN address that the United States would begin developing a major military presence and two important military bases in Greenland. The agreement also gives U.S. forces broad access for military aircraft, vessels and vehicles across Greenland and its territorial waters as necessary for defense operations. At the same time, the accord reaffirms the sovereignty and territorial integrity of Denmark and Greenland.

The agreement establishes restrictions on military and strategic activities by countries outside NATO. Non-NATO states will not be permitted to establish military installations or maintain a persistent military presence in Greenland unless the parties agree otherwise. It also places restrictions on investments and activities by non-NATO, non-EU and certain other foreign actors in sensitive sectors when they could pose a national-security or public-order threat.

Unlike a temporary defense arrangement, the new agreement has no expiration date and can only be amended by mutual consent. It also states that if Greenland eventually becomes independent through its right to self-determination, the future government would be expected to remain within NATO and assume the agreement’s rights and obligations. The accord therefore expands the U.S. military role in Greenland while leaving the island’s sovereignty unchanged under the current arrangement.