European leaders moved swiftly to back Greenland on Tuesday after Donald Trump named a special envoy to the Arctic island, sparking a new diplomatic frenzy on the continent.

Trump’s appointment of Louisiana Governor Jeff Landry as his envoy to Greenland marks another move in his gambit to annex the self-governing Danish territory. The U.S. “has to have Greenland for national security,” Trump said at a press conference on Monday.

Danish Foreign Minister Lars Løkke Rasmussen reacted with anger to the announcement and summoned U.S. Ambassador to Denmark Ken Howery for a dressing down. Defense Minister Troels Lund Poulsen called the appointment “completely unacceptable.”

Several European leaders reacted to Landry’s nomination by expressing solidarity with Greenlanders.