U.S. NATO ambassador Matthew Whitaker defends American focus on Greenland amid European backlash, calling Arctic security crucial for continental defense.

Without the United States, Nato must be Europeanised – here’s how - COMMENT: When Nato’s strongest member threatens one of its weakest, the alliance’s foundations crack. But Europe and Canada can now start preparing for a world without Washington,

The time for flattering Donald Trump is over and Europe should hit back hard economically if the U.S. imposes tariffs on NATO allies that sent troops to Greenland, ex-NATO boss and former Danish Prime Minister Anders Fogh Rasmussen said on Tuesday.

Denmark’s Prime Minister Mette Frederiksen has issued one of her strongest public warnings yet. This comes after US President Donald Trump renewed his controversial claims over Greenland. Frederiksen’s message was clear and serious.

Danish Defence Minister Troels Lund Poulsen called on Monday for NATO to do more in the Arctic, announcing that he and Greenlandic Foreign Affairs Minister Vivian Motzfeldt aimed to discuss this with NATO Secretary General Mark Rutte.

TIME spoke to legal experts about whether Trump could legally pull the U.S. out of NATO and the wider implications.

President Trump is heading to Davos, Switzerland, on Tuesday night, where he will continue his insistence that the U.S. take control of Greenland. CBS News senior White House and political correspondent Ed O'Keefe spoke with two White House officials at the World Economic Forum to learn more about the administration's stance.