What legal and political mechanisms allowed the U.S. to establish bases in Greenland without a transfer of sovereignty?
Executive summary
The United States established and expanded military bases in Greenland through a combination of wartime bilateral arrangements, a formal 1951 defense treaty with Denmark that carved out "defense areas" and permissive jurisdictional rules for U.S. forces, and a NATO political framework that normalized allied basing without transferring sovereignty; subsequent amendments and political practice preserved Danish sovereignty while granting broad U.S. operational control in specified zones [1] [2] [3]. Contemporary political debates — from Cold War-era purchase attempts to recent presidential rhetoric about acquiring Greenland — expose the distinction between legal access and political control, and reveal competing agendas behind claims about “control” of the island [4] [5] [6].
1. Wartime origins: an ambassador’s deal that opened the door
The immediate legal and political mechanism that allowed U.S. forces onto Greenland began in 1941 when Danish ambassador Henrik Kauffmann, acting in Washington while Denmark was under Nazi occupation, concluded an agreement allowing the U.S. to defend and establish installations in Greenland; that wartime arrangement spawned the initial American weather stations and airfields and set the precedent for postwar basing [1] [7] [8]. What started as emergency cooperation thus transformed into lasting presence because the United States built multiple bases during World War II and then sought to retain them in the new Cold War order [1] [4].
2. The 1951 Defense Agreement: legal architecture for bases without sovereignty transfer
The 1951 Agreement between the United States and the Kingdom of Denmark codified U.S. rights to construct, operate and freely move forces within defined "defense areas" in Greenland while leaving ultimate territorial sovereignty with Denmark — the treaty explicitly grants the U.S. exclusive jurisdiction over those defense areas for matters involving U.S. personnel and criminal offences but does not cede Danish sovereignty over the island as a whole [2] [9]. The treaty also provided practical privileges — duty- and tax-exempt entry for U.S. military supplies and personnel, immunity from certain Danish laws in defense areas, and freedom of movement for U.S. ships and aircraft conducting defense operations — giving the U.S. operational control that functions like effective administration within bases without a formal transfer of title [2] [10].
3. NATO’s political frame and the perpetuation of access
Denmark’s NATO membership and the alliance’s collective defense rationale politically reinforced the 1951 legal framework: the agreement was designed to operate within NATO’s mutual-defense context, and many of the treaty’s provisions were justified as necessary for allied — not unilateral U.S. — defense of the North Atlantic; commentators and analysts note that the U.S. ability to expand or maintain basing in Greenland is tethered to that allied framework rather than to a transfer of sovereignty [3] [9] [10]. The treaty’s longevity — and its linkage in some reporting to the existence of NATO — helps explain why Washington could continue to use Greenlandic territory for strategic infrastructure like Thule/Pituffik without absorbing the island politically [3] [10].
4. Amendments, practice and practical limits on U.S. control
Legal practice has evolved: a 2004 amendment and later understandings recognized Greenlandic self-government, clarified consultation mechanisms, and reaffirmed U.S. access to Pituffik (Thule) while stopping short of transferring sovereignty; in practice the U.S. exercises exclusive jurisdiction inside designated defense areas but must coordinate with Danish and Greenlandic authorities for changes beyond that scope, and most reporting stresses that bases operate under treaty privileges rather than ownership of territory [7] [3] [9]. The human and political costs of basing — including the displacement of Inuit communities during Cold War construction — underscore that operational control within defense zones has consequences locally even as sovereignty remains legally Danish [3].
5. Politics, purchase attempts and the difference between legal access and ownership
U.S. leaders have at times eyed Greenland for outright acquisition — Truman reportedly offered to buy it and U.S. military planners later recommended more permanent sovereign control — but those ambitions historically ran up against Danish refusal and the fact that the 1951 treaty already granted broad U.S. military rights without a sovereignty transfer [4] [5]. Recent presidential talk of “taking” or buying Greenland has reignited confusion about legal limits: analysts point out that the treaty gives Washington extensive basing rights and a fast path to expand forces, but not a mechanism to annex or unilaterally convert Greenland into U.S. sovereign territory, a distinction that reflects competing strategic aims and political messaging more than a legal blind spot [11] [6].