Professor Emeritus William C. Banks recently spoke with Newsweek about the Constitutionality of annexing Greenland.
Legally, the U.S. cannot forcefully acquire another territory, said Banks. “They couldn’t make a move like this without the approval of the Danes, as well as the Greenlanders.”
Trump himself could not annex Greenland without Congressional approval — an executive order, for example, would not have any legal authority, Banks told Newsweek. But Congress could vote to approve the annexation of Greenland, overriding international law, Banks said, although it would “be abhorrent to most Americans.” This is because the U.S. Constitution doesn’t set out any boundaries on acquiring territories.