President Donald Trump said he may impose tariffs on countries that do not support U.S. control of Greenland, telling reporters at a White House rural healthcare event on 16 January that he “may put a tariff” because the U.S. “needs Greenland for national security.” He did not specify which legal authority he would invoke. ([apnews.com](https://apnews.com/article/c8c17c89cbc4ca9819eb728102d0a2b3?utm_source=openai))
Greenland is an autonomous territory within the Kingdom of Denmark. Copenhagen and Nuuk have rejected any transfer of sovereignty, while European leaders have framed Arctic security as a shared NATO concern rather than a bilateral U.S.–Denmark matter. Denmark’s prime minister said the U.S. ambition to take over Greenland remains “intact” after talks in Washington. ([apnews.com](https://apnews.com/article/c8c17c89cbc4ca9819eb728102d0a2b3?utm_source=openai))
A bipartisan U.S. congressional delegation is in Copenhagen to signal support for Denmark and Greenland. Led by Senator Chris Coons, attendees include members from both chambers and parties, with meetings scheduled with Danish and Greenlandic officials. The delegation is cast by organisers as an attempt to “lower the temperature.” ([foreign.senate.gov](https://www.foreign.senate.gov/press/dem/release/ranking-member-to-join-bipartisan-bicameral-congressional-delegation-to-copenhagen-led-by-senator-coons?utm_source=openai))
On Capitol Hill, lawmakers have begun to codify limits. In the Senate, Senators Lisa Murkowski and Jeanne Shaheen introduced the NATO Unity Protection Act to bar State or Defence Department funding for any U.S. move to blockade, occupy, annex or otherwise assert control over the sovereign territory of a NATO member without that ally’s consent or North Atlantic Council authorisation. In the House, the Greenland Sovereignty Protection Act would prohibit federal funds for any invasion, annexation, purchase or influence campaign aimed at Greenland, while a separate Keating bill would bar funding to invade NATO countries. A rival House bill introduced by Rep. Randy Fine would authorise annexation and ultimate admission of Greenland as a state. None has advanced beyond introduction. ([murkowski.senate.gov](https://www.murkowski.senate.gov/press/release/murkowski-and-shaheen-introduce-legislation-to-cement-nato-unity?utm_source=openai))
European allies are increasing their presence around Greenland at Denmark’s request. France has begun deploying personnel and announced additional land, air and naval assets; Germany and other partners have sent small detachments for assessment and exercises coordinated with Copenhagen. Denmark’s defence ministry confirmed an expanded programme of activity in and around Greenland with allied participation. ([efe.com](https://efe.com/en/latest-news/2026-01-15/macron-announces-new-french-military-deployments-to-greenland/?utm_source=openai))
If tariffs are used as pressure, the legal route matters. A federal court last year curtailed the administration’s effort to use the International Emergency Economic Powers Act for sweeping, across‑the‑board tariffs, though sectoral measures under Section 232 of the Trade Expansion Act remain available following a national security investigation. Another pathway-Section 122 of the Trade Act of 1974-permits up to a 15% surcharge for 150 days to address balance‑of‑payments problems, but it has never been used and would likely face challenge. ([apnews.com](https://apnews.com/article/0392dbd59f548e49ad4f64254ae3f94a?utm_source=openai))
Any U.S. acquisition of Greenland would require domestic constitutional steps and international consent. Under the U.S. Constitution, territorial acquisition would ordinarily proceed by treaty with the advice and consent of two‑thirds of the Senate or by statute, and any admission to statehood is a matter for Congress. Using force to seize territory would run up against Article 2(4) of the UN Charter. ([constitution.congress.gov](https://constitution.congress.gov/browse/article-2/section-2/clause-2?utm_source=openai))
Alliance obligations are another hard limit. NATO’s treaty requires members to resolve disputes peacefully and refrain from the threat or use of force inconsistent with the UN Charter; attacking an ally would upend those commitments. Denmark’s prime minister has warned that a U.S. attack on a NATO ally would mean the end of the Alliance. ([nato.int](https://www.nato.int/docu/basictxt/treaty.htm?utm_source=openai))
Greenland already hosts a longstanding U.S. military presence at Pituffik Space Base, the northernmost U.S. Department of Defense installation, operated under the 1951 U.S.–Denmark Defence Agreement and updated arrangements in 2004. Public sources point to a permanent U.S. contingent in the low hundreds, focused on missile warning and space surveillance. ([apnews.com](https://apnews.com/article/746d67b1bc8e6681328a809787412495?utm_source=openai))
Greenland’s leadership has underlined that sovereignty is not on the table. Prime Minister Jens‑Frederik Nielsen pledged loyalty to Denmark and NATO, saying “We choose Denmark,” ahead of high‑level meetings in Washington. After those talks, Greenland’s foreign minister expressed visible distress in a live interview but reiterated that Greenland’s government will defend its people and constitutional position. ([time.com](https://time.com/7345949/greenland-denmark-trump/?utm_source=openai))
The White House has appointed Louisiana Governor Jeff Landry as special envoy to Greenland. Landry has argued publicly that engagement should run directly to Greenlandic leaders and has suggested opportunities tied to increased U.S. presence; his appointment has drawn criticism from Danish and Greenlandic voices. ([washingtonpost.com](https://www.washingtonpost.com/national-security/2025/12/22/jeff-landry-trump-greenland-envoy/?utm_source=openai))
What to watch now: any tariff step will need a durable legal basis after last year’s IEEPA ruling; the Senate–House effort to firewall funding against actions targeting NATO allies; and how Denmark’s expanded allied exercise programme in Greenland evolves. A U.S.–Nordic working group announced after Washington talks remains opaque, with Danish and U.S. readouts diverging. ([apnews.com](https://apnews.com/article/0392dbd59f548e49ad4f64254ae3f94a?utm_source=openai))