President-elect Donald Trump has sparked diplomatic controversy by suggesting the U.S. needs to acquire Greenland for reasons of “national security” and refusing to definitively rule out using military force to do so.

While Trump has cited “national security” reasons for wanting to acquire the island inhabited by about 56,000 people, there’s another big appeal that he’s been leaving out of his press conferences. Greenland is a treasure trove of minerals the U.S. needs to compete with China, and the island hasn’t been quick (enough) to fork them over.

Concerns about possible military action and its effect on NATO unity have been raised globally by Donald Trump's renewed interest in conquering Greenland. Denmark and Greenland are adamantly against any sale or invasion of the Arctic island,