Since his first term, President-elect Donald Trump has insisted that the United States should purchase Greenland - to the bewilderment of aides asked to investigate such a possibility, and despite repeated denials by top officials in Greenland and Denmark, of which the island is an autonomous territory, that it would ever be for sale at any price.

While Greenland is currently not for sale, the U.S. has purchased land and territories from other countries in the past.