Greenland, which U.S. President-elect Donald Trump wants to annex, is a self-governing Danish territory covered in ice but with untapped mineral resources — and geostrategic importance.

In December, Trump said control of the Arctic island was "an absolute necessity" for "purposes of National Security and Freedom throughout the World."

But the Republican, who takes office on Jan. 20, set off new alarm bells this week when he refused to rule out a military intervention, sparking astonishment in Copenhagen, Greenland's capital Nuuk and across Europe.