Denmark's Prime Minister Mette Frederiksen said on Friday she had ⁠agreed with NATO chief Mark Rutte that the alliance needs to boost security in ​the Arctic following weeks of ‍turmoil over U.S. President Donald Trump's threat to annex Greenland.

The governments of Denmark and Greenland, a Danish autonomous ‌territory, insist that sovereignty over the ‍island is not up for discussion, but have said they are open to talks on a wide range of other topics.

Trump said on Thursday he had secured total and permanent U.S. access to Greenland after talks with Rutte, while the NATO chief said allies would have to step up efforts to ward off threats from Russia and China in the high north.

"We agree that NATO must increase its engagement in ⁠the Arctic. Defense and security in the Arctic is a matter for the entire alliance," Frederiksen said in a social media post on Friday, along with a photo of herself and Rutte in Brussels.

Rutte said he was working with the Danish leader to enhance deterrence and defense.