The forgotten 1917 deal that explains why the “buy Greenland” idea is not as unprecedented as it sounds
When Donald Trump talks about Greenland as a strategic necessity — “we need it now” — the reaction across Europe oscillates between disbelief and indignation. Greenland is not for sale, Denmark is a NATO ally, and international law is not a menu. Yet history has a way of making today’s shocks feel less unique. Because Trump’s Greenland fixation does have a precedent — and it involves Denmark itself. A century ago, Washington pursued essentially the same logic of strategic acquisition and hemispheric security, culminating in a major territorial purchase: the Danish West Indies, sold to the United States in 1917 for $25 million in gold, and renamed the U.S. Virgin Islands. This was not just a Caribbean footnote. It was a geopolitical transaction anchored in the Monroe Doctrine, great-power rivalry, and a blunt question that still haunts Arctic politics today:
If security is at stake, do borders become negotiable?
A 2026 crisis with deep roots
Trump’s recent declarations about Greenland have reopened one of the most sensitive issues in Denmark–US relations in modern times. The argument, from Trump’s camp, is consistent: Greenland sits at the heart of Arctic security, and Russian and Chinese presence in the region makes hesitation dangerous. That framing turns a territory into a strategic object — a platform, a shield, an “asset”. And it forces Denmark and Greenland into a defensive posture: not against Russia or China, but against the unsettling possibility that a close ally can adopt the language of pressure. For Copenhagen, the shock is not merely the demand. It is the implication: that the rules-based international order may become secondary when the US defines the stakes as existential.
Denmark and the Atlantic: an empire that became a burden
In the late 1600s, Denmark acquired a foothold in the Caribbean: a cluster of islands that would later be known as the Danish West Indies (primarily Saint Thomas, Saint John, and Saint Croix). In the era of early globalisation, these territories were integrated into Atlantic trade routes and colonial extraction — brutally dependent on enslaved labour and sugar production. But by the 19th century, the Danish Caribbean was becoming increasingly unsustainable:
• Slavery was abolished in 1848
• Sugar profits declined
• Administration was expensive and distant
• The islands shifted from opportunity to liability
From Copenhagen’s perspective, the Caribbean became an uncomfortable relic — economically fragile, politically costly, morally compromised.
The Monroe Doctrine: from “no more European colonies” to “our strategic hemisphere”
The Monroe Doctrine (1823) is often summarised simply: Europe should not colonise the Americas. But the doctrine evolved, in practice, into something far more expansive — a long-term American claim to strategic primacy in the Western Hemisphere. This is where Denmark’s Caribbean islands entered Washington’s line of sight. Not as Danish property, but as strategic geography. Even before the Panama Canal existed, US military planners were already thinking in terms of maritime routes, choke points, and naval staging zones. In other words: control of islands meant control of the sea.
And control of the sea meant security.
1867: the first US attempt to buy Danish territory
The first serious US bid came in 1867, led by Secretary of State William H. Seward (the same figure behind the Alaska purchase). Seward pursued an expansionist vision sometimes described as a “Greater Republic”: America would grow not only across the continent but strategically beyond it — through diplomacy and acquisition rather than conquest. A treaty was negotiated, and Denmark’s parliament even accepted it. There was also a limited local consultation. Crucially, the treaty proposed that islanders could choose whether to remain Danish subjects or become US citizens. But the deal ultimately collapsed because the US Senate refused to ratify it. The reasons were revealing:
• domestic political chaos after the Civil War
• a bitter institutional conflict between President Andrew Johnson and Radical Republicans
• mistrust of overseas expansion beyond North America
Notably, the Senate did approve the purchase of Alaska in the same year — a reminder that Americans were more comfortable expanding into adjacent “frontiers” than acquiring tropical colonies.
1917: why Denmark sold — and why the US rushed to buy
What changed? World War I.
In wartime logic, islands become not idyllic territories but potential naval weapons. The fear in Washington was blunt: Germany could obtain a foothold in the Caribbean and threaten Atlantic routes. American anxiety sharpened dramatically after the Zimmermann Telegram, which suggested geopolitical scenarios that made the Western Hemisphere feel suddenly vulnerable. So the acquisition returned — no longer as a speculative expansionist idea, but as a security imperative. On 31 March 1917, the United States paid Denmark $25 million in gold and took control of the archipelago, renaming it the U.S. Virgin Islands. And here is the detail that resonates powerfully today: the treaty context also referenced Greenland indirectly, as the US signalled it would not oppose Denmark’s interests across the whole of Greenland. Greenland was not the main stage in 1917 — but it was already part of the strategic conversation.
The price of becoming American: “nationality without full rights”
The purchase was clean on paper, but messy in reality. For the islanders, sovereignty changed hands — yet citizenship and political rights did not arrive immediately. People lived in a strange intermediate condition: under American control, but without full constitutional inclusion. Administration initially fell to the US Navy. Democratic governance expanded only gradually. US citizenship was granted in 1927, a decade after the transfer. This is one of the most telling lessons of the entire episode: US territorial expansion can coexist with democratic self-image — but it often produces zones of partial belonging, places that are American when needed, and peripheral when inconvenient. The historian Daniel Immerwahr famously described this system as an “invisible empire”: a network of territories whose political reality does not match the rhetoric of liberty.
Greenland now: the Arctic amplifies the same contradiction
Greenland is not a Caribbean island. It is a vastly different society, geography, and historical trajectory — with autonomy, a strong Inuit identity, and a modern political ecosystem that cannot be reduced to “strategic real estate”. But the pattern is disturbingly familiar. In 1917 the logic was:
• European rivalry (Germany)
• naval security
• the Western Hemisphere as an American strategic space
In 2026 the logic becomes:
• Russia and China in the Arctic
• missile geography, satellite infrastructure, northern air routes
• the Arctic as a security theatre
Trump’s Greenland narrative pushes the same old button: security as a trump card, law as a constraint, sovereignty as negotiable. And for Denmark, the historical irony is sharp. The United States once treated Danish territory in the Atlantic as a strategic asset to be purchased. Today, it is Greenland — far more consequential — that sits under the harsh Arctic spotlight.
What this precedent really tells us
This is not merely an anecdote that makes Trump’s obsession sound less eccentric. It is a warning about structure. When the US believes strategic advantage is at stake, it has historically been willing to:
• override moral inconsistencies
• treat allies as negotiable counterparts
• reinterpret law through the lens of power
• frame expansion as defensive necessity
The 1917 Danish West Indies purchase shows that, under pressure, the world’s leading democratic power can behave like an empire — quietly, legally, even politely. The contradiction was visible then. It is louder now. And in the Arctic, where geopolitics is accelerating faster than governance, it may become the defining tension of the decade.
