Will NATO respond to a US invasion of Greenland?

Europe spent much of 2025 beefing up its defenses against Russia, but just one week into the new year, it is being forced to rethink its security again following President Donald Trump’s threat to annex Greenland.

President Trump has stepped up his calls for Greenland, a semi-autonomous Danish territory, to be brought under U.S. government control. The White House announced this week that President Trump is considering a variety of options, including military action.

Greenland, the world’s largest island, is rich in untapped mineral resources. Geographically it is located on the North American continent, but politically it is part of Europe.

Obtaining an island is no mean feat. Domestic and international political obstacles aside, any attempt to seize this territory by force would put the United States at odds with its NATO allies.

In an interview with CNN earlier this week, President Trump’s aide Stephen Miller suggested that European countries were not prepared to fight to protect Greenland. Although he did not explicitly rule out the possibility of U.S. military action in Greenland, he pointed to the island’s small population and argued that “there is no one to fight militarily with the United States over the future of Greenland, so there is no need to even think about or talk about this in the context of military operations.”

Meanwhile, Denmark and Greenland are taking talk of US military action seriously. Danish Defense Minister and Deputy Prime Minister Troels Lund Poulsen said in a statement Tuesday night that Denmark would spend 88 billion Danish kroner ($13.8 billion) to rearm Greenland, given the “serious security situation in which we find ourselves.”

Despite Denmark’s apparent desire to defend Greenland, analysts told CNBC they do not believe European forces will open fire on American forces.

Edward R. Arnold, a senior fellow at the Royal United Services Institute, a British defense think tank, told CNBC by phone on Tuesday that the White House does have the military capabilities to move into Greenland and could do so “really soon” if it wanted to.

But Arnold said there was no need for Washington to launch an operation like the one seen in Venezuela over the weekend because there would be “zero opposition.”

“What military commander in Europe is going to start using force against a U.S. military transport ship entering Greenland?” he said. “It would potentially cause a war between NATO. And the United States knows it.”

The United States has by far the largest military power among NATO members. In 2024, NATO estimated that the United States had 1.3 million military personnel, compared to 2.1 million for the rest of the alliance. The next largest number of military personnel belonged to Türkiye, with an estimated 481,000 people serving in the military.

Arnold said he expected the United States to gradually increase the number of troops in Greenland, rather than ordering a full-scale military operation or invasion.

“They didn’t try to fire,” he said of NATO forces. “So the United States is putting troops into Greenland and Europeans are in the strange position of not being able to do anything except protest politically.”

Georgios Samaras, an assistant professor of public policy at King’s College London, agreed that Greenland and the broader NATO alliance would have limited options for thwarting U.S. efforts to seize further control of the island.

“I don’t know what NATO can do to stop the United States,” he told CNBC by phone. “First of all, we’re talking about a superpower that has so many military bases across the continent that it could theoretically use to invade NATO members from within its own ranks.”

Not only does NATO have to deal with hostility to one of its own members, but it also has to consider the broader security implications of splitting with the United States, said Jamie Shea, an associate fellow in the Chatham House International Security Program and former NATO international staffer.

“A military response[from NATO]is not conceivable, because the United States can respond quickly with the limited forces that Europe can send, and it is highly unlikely that European governments would consider this,” he told CNBC. “They need all their forces to defend Europe and contribute to the European security forces against Ukraine.”

On Monday, Danish Prime Minister Mette Frederiksen warned that the US occupation of Greenland would mean the end of NATO. Of the 32 NATO members, 23 of them, including Denmark, are also members of the European Union, and have made extensive efforts to ensure that the Trump administration continues to support Ukraine.

“They would want to avoid a direct conflict with the United States that would lead to the end of NATO and U.S. support for Ukraine,” Xia said.

King’s College’s Samaras agreed that any escalation to Greenland would destroy NATO.

“When a NATO member threatens another member of the alliance, it doesn’t just provoke a quarrel; it makes the alliance’s mutual defense commitments appear conditional and political,” he said. “That would mean the end of NATO. I don’t think NATO can continue.”

Shea told CNBC that European military resistance is unlikely, but NATO has ways to pressure Washington through the European Union.

“Economics is where Europe could potentially exert influence over the United States if the EU introduces sanctions, such as tariffs or restrictions on access to American companies and investments,” Xia said.

“European governments could also deny the United States access to facilities such as European military bases and early warning radars. But these will clearly be difficult decisions for European governments, especially at a time when they are working hard to engage with the United States on Ukraine peace plans and security.”

Despite his ambition to acquire Greenland, which drives a wedge between the United States and its NATO allies, President Trump on Wednesday insisted that the United States supports the alliance, even as he slammed the organization.

In a post on Truth Social, he referenced defense spending targets for member states, saying, “Big fans of NATO, please remember that GDP is 2% and most people weren’t paying their bills until I came along.” Additionally, President Trump suggested that the alliance would not be able to prevent modern security threats without the United States’ participation.

“Russia and China have no fear of NATO without the United States. I don’t think NATO would work together for us if we really needed it,” he said. “We will always be there for NATO, even if NATO does not cooperate with us.”