US President Donald Trump announced Sunday that he will appoint a special envoy for Greenland, prompting responses from Denmark and Greenland leaders, expressing worry over potential US expansionist aims and threats to territorial integrity.

The move is unusual, as Greenland is not an independent country but an autonomous territory of Denmark. Trump made the unexpected announcement in a social media post, appointing Louisiana Governor Jeff Landry to the role.

“Jeff understands how essential Greenland is to our National Security, and will strongly advance our Country’s Interests for the Safety, Security, and Survival of our Allies, and indeed, the World,” Trump wrote.

Following the announcement, Danish Prime Minister Mette Frederiksen and Greenland Premier Jens-Frederik Nielsen issued a joint statement urging the US to respect the Arctic territory’s established sovereign boundaries. 

“We have said it before. Now, we say it again. National borders and the sovereignty of states are rooted in international law. They are fundamental principles. You cannot annex another country. Not even with an argument about international security,” the leaders said. 

Trump expressed interest in annexing Greenland during the early months of his second term. The president, in particular, referenced the territory’s strategic location and rich mineral resources as reasons the US should seek to establish “ownership and control” over it.

His comments received considerable backlash from global leaders, who argued the action would violate international law and fracture US relationships with European powers.

Danish leadership said it intends to invite the US Ambassador to Denmark, Ken Howery, to the Danish ministry in the coming days to discuss the appointment and “get an explanation.”

The appointment signals continued strain between the US and its historic European allies. Last month, the White House released a National Security Strategy that prioritizes US influence in the Western Hemisphere. The release criticized European leadership and raised concerns over the US commitment to international security agreements like NATO, of which Denmark is a member.