By Momo Yamamura, Staff Editor Volume 40
The notion of the United States taking over Greenland tends to attract attention precisely because it feels improbable in our modern international legal order. Yet the very improbability of such a proposal makes it a useful case study for examining how contemporary international law regulates territorial sovereignty and political status.
Greenland’s strategic relevance has periodically prompted public discussion about its political future. Because of its geographic position, natural resources, and existing defense arrangements, Greenland often appears in broader geopolitical conversations. Although there is no indication that Greenland’s legal status is likely to change, recurring public references to acquisition or transfer raise an important legal question: What would international law actually require if a state sought to alter Greenland’s political status? This post does not assume that any change is imminent. Instead, it uses Greenland as a lens to examine the legal principles that govern territorial change under international law.
Greenland’s Legal Starting Point
Any analysis of Greenland’s political status must begin with its current constitutional and international position. Greenland is an autonomous territory within the Kingdom of Denmark and exercises extensive self-government through its own parliament and executive. Under the Act on Greenland Self-Government, domestic matters such as education, healthcare, and natural resource management fall within Greenlandic authority, while Denmark retains responsibility for foreign affairs and defense.
From an international law perspective, Greenland is not a sovereign state. Denmark remains the internationally recognized sovereign, and Greenland does not independently conduct foreign relations. At the same time, Greenland’s autonomy, distinct population, and constitutionally protected institutions are legally significant. These features shape how international law would evaluate any proposal to alter Greenland’s political status and distinguish Greenland from territories that lack meaningful self-governance.
What International Law Allows–and Forbids
International law places strict limits on how territory may be acquired or transferred. Territorial sovereignty is a foundational principle of the international legal system, and since the mid-twentieth century, international law has rejected territorial acquisition by force. This prohibition is codified in Art. 2(4) of the United Nations Charter, which prohibits the threat or use of force against the territorial integrity or political independence of any state.
This prohibition is also firmly established as a rule of customary international law. Together, treaty law and custom create a clear baseline: Unilateral attempts to take control of territory belonging to another state, whether through military action or coercive pressure, are incompatible with contemporary international legal norms. Applied to Greenland, this framework makes clear that a forcible or unilateral takeover would be legally impermissible, regardless of strategic considerations.
Although international law prohibits acquisition by force, it does not categorically forbid territorial change. Historically, territory has sometimes been transferred through treaties concluded between sovereign states (for example, Alaska). Modern treaty law, however, imposes meaningful constraints on how such agreements may be formed and enforced, particularly with respect to consent. Central to these constraints is the requirement that treaty consent be freely given. The Vienna Convention on the Law of Treaties sets out general principles governing treaty validity, including the rule that treaties procured through coercion or the threat of force are invalid.
In the context of Greenland, these principles significantly narrow the range of lawful options. Even a negotiated agreement between states would need to satisfy the strict requirements of voluntariness and legality. Moreover, state-to-state consent alone would not resolve all legal concerns where the population of the territory has a distinct political and legal status.
Why Self-Determination Changes the Analysis
The principle of self-determination fundamentally reshapes how international law approaches Greenland’s political future. International law recognizes the right of people to freely determine their political status and pursue their economic, social, and cultural development. This principle appears in Art. 1(2) of the UN Charter and in instruments such as the International Covenant on Civil and Political Rights.
Self-determination has particular relevance for territories with autonomous governance structures or distinct populations. Greenland’s population, including a significant Indigenous Inuit majority, has exercised increasing control over internal affairs and has previously participated in referenda concerning its relationship with Denmark. As a result, any proposal to alter Greenland’s political status would likely require the freely expressed will of the Greenlandic people, regardless of whether the change involved independence, closer association, or another form of political realignment.
International law increasingly treats popular consent as an indispensable component of lawful territorial change. This shift reflects a broader evolution away from viewing territorial arrangements solely as matters between governments and toward frameworks that account for the rights and interests of affected populations.
Importantly, international law does not prohibit cooperation between states and non-sovereign territories. Defense agreements, economic partnerships, and scientific collaboration are all permissible when conducted with appropriate consent. The existing defense relationship between the United States and Denmark, including the long-standing U.S. presence at Thule Air Base, demonstrates how strategic cooperation can occur without altering sovereignty.
North Atlantic Treaty Organization (NATO) membership does not alter this legal framework. Denmark is a founding member of the NATO, and Greenland has long played a role in NATO’s collective defense posture through existing basing and defense agreements. However, NATO is a collective defense alliance, not a mechanism for territorial change. The Treaty does not authorize the transfer of sovereignty, nor does it displace core principles of international law governing territorial integrity and self-determination. Even within a NATO context, changes to political status remain subject to the same legal constraints of consent and popular will.
Greenland ultimately offers a useful case study for understanding how contemporary international law approaches questions of territory and sovereignty. It illustrates how principles governing the use of force, treaty consent, and self-determination operate together to constrain unilateral action and prioritize lawful participatory processes. Even when proposals remain hypothetical, examining their legal implications serves an important function. Legal analysis clarifies the boundaries of lawful conduct and reinforces the role of international law in managing strategic interests through rules rather than power alone. Ultimately, Greenland’s status reflects a broader transformation in international law. Territorial change is no longer understood as a function of capability or advantage. Instead, it is governed by a legal framework that emphasizes consent, legitimacy, and respect for both states and people.