U.S. President Donald Trump’s rationale for decapitating Venezuela’s government is fueling concerns among European officials that they could soon face an existential dilemma over Greenland.

Trump over the weekend explained his decision to detain Venezuela’s leader and have the U.S. run the country as a modern revival of the 19th-century Monroe Doctrine — the “Donroe Doctrine,” as he dubbed it. The principle essentially claims a U.S. right to lead the entire Western Hemisphere, and to control any critical assets within it.

To Trump, that includes Greenland.