Trump Wants Greenland. Can a President Buy Territory?

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President Donald Trump‘s White House confirmed on January 7, 2026, that acquiring Greenland is a national security priority and that using military force is always an option for making it happen. This wasn’t a slip of the tongue or an off-the-cuff remark—it was an official White House statement about using military force against a NATO ally.

The president cannot do this. Not under the Constitution.

Constitutional Requirements for Territorial Acquisition

The Constitution gives Congress the power to admit new states but doesn’t specify how the country acquires territory initially. Two centuries of practice established the pattern: the president negotiates, then the Senate votes to approve it (needing two-thirds agreement), and Congress passes legislation to integrate the new territory and pay for it.

Every major territorial acquisition in American history followed this path. The Louisiana Purchase in 1803—828,000 square miles for $15 million—required the Senate to vote to approve it 24-7. Alaska in 1867, purchased from Russia for $7.2 million, went through the same process. The Danish West Indies, which became the U.S. Virgin Islands in 1917, required a treaty ratified by the Senate and implemented through congressional legislation. Texas joined through a special vote in Congress in 1845 rather than a treaty, but that still meant votes in both chambers and a presidential signature.

James Madison explained why in an 1789 letter to Thomas Jefferson. The Constitution recognizes “what the History of all Governments demonstrates, that the Executive is the branch of power most interested in war, and most prone to it.” Therefore, “with studied care,” it gave Congress the power to decide about war. The Framers didn’t trust any single person with the power to expand the nation’s borders through force.

Presidential War Powers and Congressional Authority

The president’s role as Commander in Chief does not include the power to start a war without Congress approving it. The Constitution gives Congress, not the president, the power to decide when, where, and whom the United States goes to war. An attack on Greenland would target a NATO ally for the explicit purpose of territorial conquest.

Any action targeting Greenland would activate NATO’s rule that an attack on one member means all members must defend it. Denmark would be entitled to invoke its requirement to defend each other, meaning every NATO member would technically be required to defend Denmark against the United States.

Danish Prime Minister Mette Frederiksen stated on January 6: “If the United States chooses to attack another NATO country militarily, then everything stops. That is, including our NATO and thus the security that has been provided since the end of the Second World War.” NATO cannot survive if its most powerful member attacks a smaller member to seize territory.

Greenland’s Self-Government Status

Greenland isn’t Danish property that Denmark can sell. It’s a territory that governs itself under the 2009 Self-Government Act, which says Greenlanders have the right to decide their own future. The island has a population of about 57,000, predominantly Inuit, concentrated along the western coast.

Any change in Greenland’s sovereignty requires consent from Greenland’s parliament, approval by referendum among Greenlanders, and consent from Denmark’s parliament.

Greenlanders have made their position clear. A 2025 poll showed 85 percent oppose becoming part of the United States. Prime Minister Jens-Frederik Nielsen issued a statement on January 6: “Threats, pressure, and talk of annexation have no place between friends. Enough is enough. No more pressure. No more innuendo. No more fantasies about annexation.”

International Law Prohibits Territorial Conquest

The UN Charter bans using force to seize territory. The United States ratified this and is bound by it. It explicitly prohibits “the threat or use of force against the territorial integrity or political independence of any state.”

A treaty doesn’t count if it was made under threats or force in violation of the principles of international law embodied in the Charter of the United Nations. Even if Trump negotiated a treaty for Greenland’s transfer, it would be void under international law if obtained through threat or use of force.

International law recognizes that people have the right to self-determination, distinct from and superior to the strategic interests of more powerful states. The UN Declaration on the Granting of Independence to Colonial and Dependent Peoples affirms that “the subjection of peoples to foreign control and exploitation constitutes a denial of fundamental human rights.” Even if Denmark agreed to transfer Greenland—which Denmark has categorically rejected—such a transfer would remain illegitimate under international law if Greenlanders themselves didn’t freely consent.

The National Security Argument

Trump has justified his interest in Greenland by claiming it’s “covered with Russian and Chinese ships all over the place” and that “we need Greenland from the standpoint of national security, and Denmark is not going to be able to do it.”

The United States has what it needs in Greenland. Pituffik Space Base has been there since 1943 and operates as part of American missile defense and early warning systems. A 1951 U.S.-Denmark Defense Agreement allows the United States to maintain bases in Greenland and, if necessary, to establish additional bases as deemed necessary by NATO. During the Cold War, the U.S. stationed up to 10,000 troops across multiple camps throughout Greenland. There is no benefit from territorial control that couldn’t be achieved through the existing framework.

The administration has emphasized Greenland’s mineral wealth—rare earth elements, lithium, graphite, and other materials needed for batteries and equipment. Greenland contains 25 of 34 minerals Europe needs for technology and defense. But Greenland hasn’t granted substantial mining concessions despite years of interest from international companies. Many Greenlanders oppose rapid mineral extraction that would transform their island’s environment. If Greenland’s minerals were valuable enough to justify acquisition, companies would already be working with Greenland to develop its minerals. You don’t need to conquer a place to do business there.

Republican Opposition

The administration has encountered strong opposition from Republicans who generally support Trump’s foreign policy initiatives.

House Speaker Mike Johnson stated that action targeting Greenland would “not be appropriate.” Representative Don Bacon of Nebraska called the rhetoric “appalling” and “one of the silliest things” to emerge from the White House, emphasizing that “Greenland is a NATO ally” and “Denmark is one of our best friends,” such that “the way we’re treating them is demeaning and it has no upside.”

Senator Lisa Murkowski of Alaska warned that “any effort to claim or take the territory by force would degrade both our national security and our international relationships.” Senate Majority Leader John Thune issued a statement with Democratic Senator Jeanne Shaheen stating that the United States “must keep the promises we made in treaties” and “respect that Denmark controls its own territory.”

Senator Ruben Gallego introduced an amendment to the military funding bill explicitly prohibiting the use of funds “for military force, the conduct of hostilities, or the preparation for war with respect to Greenland.” He stated: “Congress will not pay for illegal military action in Greenland to soothe the ego of a president who wants to act beyond his constitutional powers.”

Any territorial acquisition requires Senate ratification of a treaty by a two-thirds majority and congressional legislation to integrate the territory and appropriate funds. Those votes aren’t happening.

The Venezuela Operation as Precedent

The administration’s recent capture of Venezuelan President Nicolás Maduro raises a concern about whether the administration will disregard constitutional limits.

The Venezuela operation involved bombing and attempts to overthrow the government of a sovereign nation without congressional authorization, without any immediate threat to America, and without the kind of immediate threat the Constitution allows for. Constitutional law experts concluded unambiguously that it violated the Constitution, which gives Congress the power to declare war.

The operation differed from the 1989 invasion of Panama, which at least occurred after Panama declared a “state of war” with the United States and Panamanian forces attacked American servicemembers. Venezuela made no declaration of war, launched no attack on American territory or forces, and posed no immediate threat. The administration proceeded without notifying Congress in advance, much less obtaining authorization.

If the administration attacked Greenland under the theory that national security justifies action without congressional authorization, it would be going further with constitutional violations than the Venezuela operation, moving from overthrowing a government in South America to territorial conquest targeting a NATO ally.

Multiple bills to limit further military action in Venezuela have failed to pass Congress, with Senate Majority Leader Thune and other Republicans declining to support measures limiting presidential authority. But the bipartisan opposition to Greenland action appears stronger. Republicans who supported or tolerated the Venezuela operation have explicitly opposed any Greenland invasion, suggesting that attacking a NATO ally crosses a line that attacking Venezuela did not.

International Allied Response

European leaders have rallied in explicit and unified support for Denmark and Greenland. France, Germany, Italy, Poland, Spain, and the United Kingdom issued statements reaffirming that “Greenland belongs to its people” and that “it is for Denmark and Greenland, and them only, to decide on matters concerning Denmark and Greenland.”

Canadian Prime Minister Mark Carney stated that “the future of Greenland and Denmark are decided solely by the people of Denmark” and announced that Canada’s Governor General and Foreign Minister would visit Greenland in February 2026 to demonstrate Canadian support.

Representatives Blake Moore and Steny Hoyer, co-chairs of the Congressional Friends of Denmark Caucus, characterized the discussion of annexation as “dangerous and unnecessary” and warned that “an attack on Greenland—an important part of that alliance—would tragically be an attack on NATO.”

Constitutional Limits and Congressional Action

The administration faces obstacles from the Constitution, international law, and politics to acquiring Greenland through any pathway. Denmark won’t sell. Greenland won’t consent. The Senate won’t ratify. Congress won’t authorize force. NATO would collapse. International law prohibits conquest. And 85 percent of Greenlanders oppose American control.

What matters is whether Congress will respond with clear constitutional limits that make such talk more than rhetoric. The Venezuela operation suggests the administration may be testing how far it can push executive authority before Congress pushes back with legislation rather than statements.

Greenlandic influencer Qupanuk Olsen told journalists in June 2025 that Trump’s words felt threatening. After the Venezuela operation in January 2026, she observed that “Trump’s words were no longer just words” and that the “threats to annex Greenland feel much more realistic.”

When the president talks about using force targeting allies, Congress, courts, and voters need to remind him that the Constitution doesn’t work that way. Territorial acquisition requires congressional consent through treaty ratification and implementing legislation. Offensive war requires congressional authorization. These aren’t minor details—they’re fundamental checks on executive power that have governed American territorial expansion for more than two centuries.

Congressional action will determine whether constitutional limits on executive power remain meaningful. Statements of opposition matter, but legislation matters more. The amendment Senator Gallego introduced to prohibit funding for military action in Greenland represents the kind of concrete constraint that could prevent unconstitutional action.

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