U.S. President Donald Trump said on Sunday that Denmark has not been able to do anything to remove the "Russian threat" from Greenland, adding, "Now it is time, and it will be done!!!"

"NATO has been telling Denmark, for 20 years, that 'you have to get Russian threat away from Greenland.' Unfortunately, Denmark has been unable to do anything about it," Trump wrote in a post on the social media platform Truth Social.

The White House and Denmark's foreign affairs ministry did not immediately comment on Trump's new move.

Trump has repeatedly insisted he will settle for nothing less than ownership of Greenland, an autonomous territory of Denmark.

Leaders of both Denmark and Greenland have insisted the island is not for sale and does not want to be part of the United States.

Trump on Saturday vowed to implement a wave of increasing tariffs on European allies until the U.S. is allowed to buy Greenland. Danish and other European officials have pointed out that Greenland is already covered by NATO's collective security pact.

Russia, meanwhile, said it was unacceptable for the West to keep claiming that Russia threatened Greenland, and argued that the crisis over the territory exposed the double standards of Western powers that claim moral superiority.

(With input from Reuters)