President Donald Trump has repeatedly said he wants to take over the Arctic island for security reasons -- to the anger of Copenhagen, a longstanding US ally and NATO member.

"Denmark should focus on the fact that the Greenlanders don't want to be a part of Denmark," Rubio said after a meeting with NATO foreign ministers in Brussels.

"What we're not going to do is let China come in now and offer them a bunch of money, and become dependent on China."

Polls show a vast majority of Greenland's 57,000 people want to become independent from Denmark but do not wish to become part of the United States.

During a trip to the island last week US Vice President JD Vance made it clear that Washington was going to "respect the self-determination of Greenlanders," Rubio said.

Both Nuuk and Copenhagen viewed the visit as a provocation.

On Thursday, Rubio had reassured his Danish counterpart of the "strong" ties between the two countries, after a meeting on the sidelines of the NATO talks.