Denmark's King Frederik X will visit the semi-autonomous Danish territory of Greenland on Monday, in a show of opposition against United States President Donald Trump's aim to take over the island.

Frederik's office said the king, who is Denmark's figurehead but who does not have official political power, will visit the massive, mineral-rich Arctic island with Greenland's Prime Minister Jens-Frederik Nielsen. Nielsen and the king will travel to the island together, after Nielsen visits Denmark on Saturday to meet Denmark's Prime Minister Mette Frederiksen.

Frederiksen said the governments of Denmark and its semi-autonomous territory are in full agreement that Greenlanders are the only ones who should decide the territory's future.

"We live in a time that calls for unity," Frederiksen said. "We must support each other in the difficult foreign policy situation that Greenland and the Danish realm currently are in."

Nielsen told Greenland's Sermitsiaq daily newspaper he plans to talk to Frederiksen about the geopolitical situation and the future of ties between Denmark and Greenland.

The king's upcoming visit to Greenland and the visit of Greenland's prime minister to Denmark follow Trump declaring he will control Greenland "one way or another" and that the US needs it because of its strategic importance and its reserves of raw materials.

Controversially, Trump has not ruled out using force to take the island, even though Denmark is a NATO member.

Trump sent US Vice-President JD Vance to Greenland last month for a visit that was criticized by both Denmark and Greenland. During the trip, Vance said Denmark had not done enough to keep the island safe from nations wanting to control it.

The upcoming visits of the king and of Greenland's prime minister follow Frederiksen's visit to Greenland earlier in April, when she vowed the US "shall not take over Greenland" and suggested the nations instead increase defense collaboration.

Nielsen has also rejected Greenland becoming part of the US and wrote on Facebook last month: "President Trump says that the United States 'will get Greenland'. Let me be clear: The United States will not get it. We do not belong to anyone else. We decide our own future."

According to recent opinion polls, 80 percent of Greenlanders want full independence from Denmark and 85 percent do not want to become part of the US. Only 6 percent like the idea.

Reuters said the relationship between the governments of Denmark and Greenland has been strained at times but Greenland's 57,000 residents like Frederik and the royal family.

During his visit, the king will tour the capital Nuuk and the Station Nord military outpost in the far north, where he will meet members of Sirius Patrol, an elite team that uses dog sleds to conduct patrols.