US President Donald Trump, Danish Prime Minister Mette Frederiksen, and Greenlandic Prime Minister Jans-Frederik Nielsen participate in a trilateral signing ceremony at United Nations Headquarters in New York, 22 September 2026. Official White House Photo/Daniel Torok via Flickr

On 22 September, the US, Denmark and Greenland signed a defence agreement, ending months of tensions over ownership of the Arctic island. The agreement has widely been viewed as a victory for the collective strength of the middle powers.

The security pact, signed on the sidelines of the UN General Assembly in New York, permits Washington to build two military bases and expand its existing Pituffik Space Base in Greenland – an autonomous territory belonging to Denmark, a fellow NATO member.

Federica D’Alessandra, Co-Chair of the IBA Rule of Law Forum, says the agreement successfully subverts the Trump administration’s expansionist rhetoric with a conventional treaty-based solution. ‘There is no annexation, purchase, sovereign-base territory or unilateral American authority to redraw borders,’ she says. ‘Instead, there is a negotiated trilateral agreement expressly founded upon sovereignty, territorial integrity, self-determination, human rights and the rule of law. Denmark’s government had presented precisely those principles as its red lines.’

Connor McPartland, an associate director with the Atlantic Council’s Transatlantic Security Initiative, says the trilateral agreement signals the growing strength of middle powers in standing their ground. ‘The support of Denmark’s fellow NATO allies and EU members was instrumental in putting enough pressure on the United States to begin serious negotiations away from the spotlight,’ he says.

Although some have hailed the agreement as a rebuke of the Trump administration’s increasingly coercive approach to diplomacy, Elsa Wyllie, an officer of the IBA War Crimes Committee, believes the pact was probably ‘the least bad’ option for both Greenland and Denmark. ‘What is new is narrow: two pre-agreed defence areas, express undersea access, a say over sensitive investment from outside NATO and the EU, and an agreement with no end date,’ she says. The US initially made significant demands, but ended up with modest gains, ‘and that is the lesson other capitals will draw.’

The agreement explicitly prohibits non-NATO countries, such as Russia and China, from establishing military facilities on the island or investing in Greenland’s vast mineral wealth. Although Denmark has blocked previous bids by Chinese state-owned companies, McPartland – who served as Deputy Director for Arctic and Oceans Policy within the US Department of Defense – says this now gives Washington ‘increased influence’ over which third-party investments in Greenland might constitute a national security risk.

Even if this has limited practical impact in the short-to-medium term, McPartland says middle powers should take note, particularly given the US administration’s increasingly concerted efforts to gain access to the mineral resources of other nations. The 2025 US-Ukraine mineral agreement and the recently inked deal for access to around 20 per cent of Venezuela’s oil reserves are two cases in point, he says.

The security agreement was welcomed by NATO Secretary-General Mark Rutte, who said that the pact, ‘along with NATO’s growing role in securing this vital region,’ has enhanced the alliance’s ‘collective security and supports a safer and more stable future for us all.’

However, Wyllie – an international human rights and criminal defence lawyer with Arendt Chambers in Vancouver – says the protracted negotiations and final agreement may also serve as a cautionary tale for the alliance of middle powers. ‘We need to be honest about the gap between our rhetoric and our conduct: Mark Carney’s warning at Davos, “if we’re not at the table, we’re on the menu,” has become the rallying cry of the middle-power moment. It is not yet a description of how middle powers, Canada included, actually behave,’ she says. ‘Carney himself said that criticising intimidation from one direction while staying silent when it comes from another is “keeping the sign in the window.”’

Wyllie believes the agreement should prompt the middle powers to build collective structures that allow them to leverage their influence effectively and hold their ground in the face of similar tactics on the global stage in future. ‘What is rational now is to build those structures before the pressure arrives, so that the next capital to face it’ has the backing and support of other states, she says.

The White House has lauded the agreement as historic. Although the outcome may provide some useful lessons for how middle powers deal with greater powers in future, McPartland is concerned about the lasting damage that the US administration’s belligerent approach to Greenland has done to its reputation on the world stage. ‘The collateral damage from the crisis’ has greatly impaired Washington’s standing with its allies, ‘which shows the shortcomings of the administration’s approach,’ he says.

The success of the agreement, which still requires approval from both Denmark’s and Greenland’s parliaments, will hinge on how it plays out in practice, says D’Alessandra, a non-resident fellow at the Carnegie Endowment for International Peace. ‘The question now becomes how will the agreement be implemented,’ she says. For example, there are questions as to where the additional bases will be located, how communities are to be affected and whether environmental and cultural protections will have practical force. Also to watch, she says, will be ‘how investment restrictions affect Greenland’s economic choices and whether its population retain meaningful democratic control over an expanding and effectively permanent American military footprint.’