President Donald Trump's interest in buying Greenland is "not a joke," Secretary of State Marco Rubio said in an interview on Thursday, adding that acquiring Greenland was in U.S. national interest and needs to be solved.

Rubio said he could not predict if Trump would succeed in buying Greenland from Denmark or restoring American authority over the Panama Canal while he is in office.

Secretary of State Marco Rubio called President Trump's desire to buy Greenland in the "the national interest" of the U.S. during an interview Thursday. The big picture: Trump has doubled down on his push for Greenland since winning the presidential election,