If the U.S. were to use military force to acquire another nation’s territory (such as Greenland), would it harm NATO and allied relations?

In 2026, Donald Trump reignited debate over acquiring Greenland, calling it strategically vital and suggesting the U.S. could purchase it or even take it by force if necessary.

Greenland is part of Denmark, a founding member of NATO, and Danish leaders quickly condemned the idea.

Officials warned that any military attempt to seize Greenland would be treated as an act of aggression against Denmark, triggering NATO's Article 5 mutual defence clause.

The proposal alarmed European allies, who said it risked fracturing transatlantic trust, violating international law, and destabilizing the alliance by showing disregard for the sovereignty of fellow member states.