The United States is exerting “unacceptable pressure” on Greenland, Denmark’s Prime Minister Mette Frederiksen said on Tuesday, ahead of an unsolicited visit by a high-profile U.S. delegation to the semi-autonomous Danish territory this week.

Greenland has accused the Trump administration of being “highly aggressive” by sending a delegation of senior officials to the territory this week.

President Donald Trump’s national security adviser Mike Waltz is visiting Greenland early this week with the U.S. energy secretary Chris Wright, according to reports, in addition to a separate trip by Second Lady Usha Vance on Thursday.

The trips come after Trump’s repeated threats to annex the autonomous territory.

Vice president says he will travel to Greenland on Friday, joining his wife

Leaders in Greenland had viewed the second lady’s trip as an escalation in President Donald Trump’s push for the United States to annex Greenland, and adding the vice president to the trip signals a more serious tone from the White House.

Reuters/ WP