WASHINGTON — President Donald Trump announced Friday that the United States had reached an emerging security agreement with Denmark and Greenland that would expand the American military presence on the Arctic island without transferring control of the territory to the United States. The agreement is expected to be signed next week during the United Nations General Assembly, Danish Prime Minister Mette Frederiksen’s office said. It will not take effect until it receives approval from the Danish and Greenlandic parliaments. The pact was negotiated quietly for months by officials from all three governments. Its terms would give the United States expanded authority over security matters in Greenland, restrict non-NATO military bases and limit investments by countries viewed as adversaries. A State Department official, speaking anonymously because the official was not authorized to comment publicly, said the agreement would prevent China and Russia from establishing a base in Greenland. Trump said in a social media post that the deal gives the United States “permanent control over security” and other U.S. needs in Greenland. He said his administration would begin developing a larger military presence immediately. Frederiksen said the agreement recognizes the sovereignty and territorial integrity of both Greenland and Denmark, as well as their right to self-determination. Greenland Prime Minister Jens-Frederik Nielsen said the deal serves the interests of all three governments and acknowledges Greenland’s concerns. The announcement follows an unusually sharp dispute between Washington and its NATO allies. Since returning to the White House, Trump has repeatedly said the United States should acquire Greenland, which is an autonomous territory within the Kingdom of Denmark. He has declined to rule out military action, while Danish and Greenlandic officials have insisted that the island is not for sale. Greenland has about 56,000 residents and is rich in minerals. More than two-thirds of its territory lies north of the Arctic Circle, placing it near strategically important air and sea routes between North America and Europe. Its location has made the island central to North American defense since World War II. The United States already operates Pituffik Space Base in northwestern Greenland. Built under a 1951 defense agreement with Denmark, the installation supports missile-warning, missile-defense and space-surveillance operations for the United States and NATO. Washington previously maintained several other military facilities on the island before reducing its presence after the Cold War. Secretary of State Marco Rubio called the new pact a “historic deal” and said it would keep Greenland within North America’s strategic defense area while excluding adversaries from the territory and surrounding region. The agreement could ease a dispute that had unsettled the NATO alliance, but experts said the damage caused by Trump’s threats will not disappear quickly. Imran Bayoumi of the Atlantic Council said the demands had harmed the United States’ standing in Europe and were viewed by Greenlanders, Danes and other Europeans as an attack on their sovereignty. The pact’s final impact will depend on its detailed language and the pending parliamentary votes in Denmark and Greenland. Until those steps are completed, the proposed expansion of the U.S. military role remains an announcement rather than an enforceable agreement.