The Danish West Indies Precedent for U.S. Acquisition of Greenland
There is lots of law between Donald Trump and the acquisition of Greenland
President-elect Donald Trump’s gambit for Greenland, an autonomous territory of Denmark, is not the first time the United States has sought to acquire an island from Denmark “for purposes of national security,” as Trump recently stated. In 1917, Denmark sold the United States the “Danish West Indies”—today, Saint Thomas, Saint John, and Saint Croix—for $25 million. The history of that purchase, which has parallels with the Trump ploy, illustrates some of the intricacies under international and domestic law that would be involved in any acquisition of Greenland by the United States.
The Long Negotiation for the U.S. Virgin Islands
One reason Trump wants Greenland is to prevent other countries from influencing or dominating the island. He said of the island last week: “You look at — you don't even need binoculars — you look outside. You have China ships all over the place. You have Russian ships all over the place. We’re not letting that happen.”
A similar concern motivated President Abraham Lincoln and his Secretary of State, William Seward, to acquire the Danish West Indies that Denmark had acquired through colonization and purchase in the 17th and 18th centuries. U.S. diplomats had warned Seward that the islands were “vulnerable to the acquisitive designs of a number of European powers,” including Great Britain and Austria, as William Boyer notes in his history of the American Virgin Islands. The Civil War also taught Lincoln and Seward “the danger of having an unprotected Atlantic coastline,” especially since “all the important naval powers except the United States had possessions in the Caribbean.”
Seward broached the topic of a sale with the Danish ambassador in January 1865, but the assassination of Lincoln and near-assassination of Seward on April 14, 1865 delayed negotiations. By 1867, a recovered Seward had crafted a treaty with Denmark to purchase two of the three islands, St. Thomas and St. John, for $7.5 million. The treaty guaranteed the islanders a referendum on the cession, liberty and property protections, and a choice of U.S. or Danish citizenship. Denmark quickly ratified the treaty. But the treaty died in the U.S. Senate after submission by President Johnson, in large part due to the “animosities and political passions” related to Johnson’s impeachment, Boyer says.
Negotiations resumed in 1892 and continued sporadically over the next decade, resulting in a 1902 treaty text for the sale of all three islands. The U.S. Senate consented and President Theodore Roosevelt ratified the treaty. But this time Denmark declined to ratify—in part because the treaty did not provide for a referendum on the sale by the Virgin Islanders.
U.S. interest in the islands renewed at the dawn of World War I. “The opening of the Panama Canal in 1914 and the possibility that the United States might be drawn into the war against Germany heightened America’s security interests in acquiring the Islands,” says Boyer. The United States saw the Danish West Indies as strategically important for protecting shipping lanes in the Caribbean Sea, for securing the canal, and for projecting naval power more generally in that part of the world. The Danish ambassador told Secretary of State Lansing in 1915 that Denmark “would not negotiate upon the subject,” in part because the Panama Canal had enhanced the commercial value of the islands.
Lansing subsequently informed the ambassador that the United States might seize the islands if Denmark gave them up, by consent or force, to a European power, and especially to Germany. “This plain spoken threat of what might occur under certain conditions had the desired effect,” Lansing reported to President Wilson. Fifty-two years after the original negotiation, the United States and Denmark reached agreement in the “Convention between the United States and Denmark for the Cession of the Danish West Indies,” which both nations had ratified by January 1917.
Domestic Issues
Beyond Senate consent, which was needed to effectuate the treaty, Congress had to act. The Act of March 3, 1917 appropriated $25 million to pay for the islands and an additional $100,000 for its governance. It also established the position of Governor of the Islands (to be appointed by the President with Senate consent). The Governor possessed “all military, civil, and judicial powers necessary,” though in practice carryover colonial councils played a governance large role. (The details about subsequent domestic governance of the Virgin Islands can be found in Boyer.)
The U.S.-Denmark Convention granted “citizenship in the United States” to those who did not preserve Danish citizenship. The State Department, however, took the position that Virgin Islanders had American “nationality” but not “citizenship,” according to Boyer. Congress responded in 1932 by granting citizenship to “all natives of the Virgin Islands.” But this “statutory citizenship” might be reversible by Congress. And the D.C. Circuit held in 2015 that birthright citizenship does not apply to unincorporated territories like the Virgin Islands. The Supreme Court has not addressed this issue and denied a petition for a writ of certiorari that raised it in 2022.
Trump, Denmark, and Greenland
The parallels between the Danish West Indies saga and the Trump play for Greenland are remarkable: The president will be seeking to acquire an island from Denmark for security reasons that are nominally linked to the Panama Canal (though Trump’s interests in Greenland and the canal are complementary strategic concerns about countering China’s influence and projecting military and economic power, and are not formally linked as the canal and the Virgin Islands were in 1917). Greenland is resisting the overture. And the U.S. government is vaguely threatening coercion.
Trump last week refused to rule out military and economic coercion in his effort to acquire Greenland. Any threats or use of force against Greenland, if repeated as president, would violate Article II(4) of the U.N. Charter. Trump does not care about the Charter, and would not be the first president to violate it. An invasion of Greenland would also exceed the weak domestic-law constraints on a president’s unilateral use of offensive force established by the Office of Legal Counsel. Trump does not care about those rules either. But the U.S. military as an institution has traditionally cared about at least a plausible stance on domestic and international legality. I expect Trump to bluster about using force but not use it in the end, since it would as a practical matter create monumental political headaches compared to other options for securing Greenland.
The other options are non-military carrots and sticks. Trump has already threatened Denmark with tariffs at “a very high level” (too bad for The Lego Group and Novo Nordisk, the maker of Ozempic). He could threaten to limit U.S. investment in Denmark or in Danish companies. He could also link Greenland to U.S. support for NATO—a commitment that Trump has long questioned. It is already mind-boggling that Trump floated using military force to acquire a territory of a NATO ally; tying any future U.S. role in NATO to the Greenland acquisition would significantly raise the heat not just on Denmark but on all NATO countries. On the carrots side of the equation are cash and pledges of investment in both Denmark and Greenland.
The negotiation over the Danish West Indies points to some of the complexities that would arise with any negotiation with Denmark and Greenland over the island. One is the wishes of the people of Greenland. Islander preferences were a sticking point throughout the five-decade negotiation with Denmark. The matter is much tricker with Denmark and Greenland since the latter is semi-autonomous and possibly seeking independence.
There are also complex questions about citizenship rights for Danish citizens on Greenland (including a possible option to remain a Danish citizen and keep freedom of movement rights in the European Union); how the strange property rights on Greenland will be maintained or altered; the continuance, or not, of various political, civil, and social rights; the new governance structure for Greenland; and the status of the indigenous Inuit people on Greenland.
Trump, Greenland, and Congress
Whatever deal Trump may strike, he almost certainly cannot carry it out without getting Congress on board. The Constitution grants Congress authority “to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States.” But it does not expressly provide for the acquisition of new territory. (Jefferson the strict constructionist famously believed that the Louisiana purchase was unconstitutional even though he ratified the treaty that made it possible).
Almost every significant acquisition of U.S. territory has involved Congress or the Senate. The few tiny counterexamples cited by the Office of Legal Counsel in justifying President Reagan’s proclamation to extend the territorial sea—mainly, the Midway and Wake Islands—involve acquisitions of uninhabited territory that lacked an adverse foreign sovereign claim. Even in this context, OLC acknowledged, “the practice may be subject to some constitutional question.”
One might be cynical about any practice-based legal constraint on Trump. With a pliant Attorney General or OLC head, might not Trump get sign-off for a unilateral executive agreement that makes Greenland a U.S. territory without going to Congress?
Such a move would likely spark a court fight. Even with the unusual property arrangements on Greenland, someone would surely have standing. Trump might well lose a judicial battle, given the sketchy originalist basis for a unilateral presidential acquisition power, longstanding congressional involvement, the OLC concession even in the context of acquiring unchallenged land, and the Boumediene statement that the Constitution “grants Congress and the President the power to acquire, dispose of, and govern territory.” The uncertain validity of a unilateral presidential deal might also adversely affect the stability of property arrangements in Greenland.
Perhaps most importantly, Congress has an ultimate say because only it can pay for the deal. I don’t see how Trump can get around that.
Conclusion
“Trump's threats [against Greenland] may be mere trolling,” says the former U.S. Ambassador to Poland, Daniel Fried. “Trump seems to relish saying things that send people scurrying, chattering, and expressing outrage.”
Trump’s public musings about Greenland have already had this impact in Europe. And more: Denmark has signaled an interest in concessions short of a sale, and Greenland’s prime minister says he is “ready to talk” to Trump. Trump has a habit of making the unthinkable thinkable. But he faces complex legal and political hurdles to making the thinkable a reality.
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Odds and Ends:
Bob in the Atlantic on the Trump DOJ 2.0
Morgan Lewis, Trump 2.0 Conflict of Interest White Paper
Quinta Jurecic in the Atlantic on how law can constrain Trump 2.0
Quinta Jurecic in the New York Times on why voters dismissed Trump’s lawbreaking
Michael Hirsh in Politico on U.S. Military worries about domestic deployments