France has warned President-elect Donald Trump against threatening the territorial integrity of the European Union after he refused to rule out military force to obtain Greenland.

The French foreign minister Jean-Noël Barrot told France Inter radio he does not believe the U.S. would launch a military campaign to secure Greenland but conceded the world has “entered an era that is seeing the return of the law of the strongest,” per The Guardian.

Ahead of his inauguration, Trump has repeatedly made remarks about the U.S. potentially acquiring Canada and Greenland. What were initially humorous propositions have rapidly evolved into potential realities, albeit very unlikely.

Earlier this week, Donald Trump Jr. flew to Greenland in an apparent nod to his father’s ambitions of acquiring the world’s largest island.

Last month, the incoming president said, “ownership and control of Greenland is an absolute necessity” for the U.S., per the BBC.

Greenland is rich in natural resources and has a relatively small population of just 57,000. While it belongs to Denmark and is a member of the EU, Greenland has maintained home rule since 1979.

Both the Danish prime minister, Mette Frederiksen, and Greenland’s premier, Múte Egede, say the decision to join the U.S. is up to the people of Greenland.

“There is a lot of support among the people of Greenland that Greenland is not for sale and will not be in the future either. Greenland belongs to the Greelanders,” Frederiksen said, per The Guardian.

Canada and Greenland have not been Trump’s only foreign focus. Trump has also stated that he believes the Panama Canal should return to U.S. control if the country does not change how the waterway is managed. Trump referred to the canal as a “VITAL National Asset.”