Danish police sent extra personnel and sniffer dogs to Greenland as the icy island steps up security measures ahead of a planned visit this week by second lady Usha Vance, the chief spokesman for Denmark’s national police said.

René Gyldensten said Monday the extra officers, deployed the day before, were part of regular steps taken during visits by dignitaries to Greenland, a self-governing, mineral-rich territory of American ally Denmark.

Citing office procedure, Gyldensten declined to specify the number of extra police flown on the chartered flight. News reports put the number at dozens of officers.

Vance’s visit comes at a time when President Donald Trump has suggested the United States should take control of Greenland.

Greenlandic news outlet Sermitsiaq posted images of two U.S. Hercules workhorse military aircraft on the tarmac Sunday in Nuuk, the capital, adding that the planes later departed.

Vance will leave on Thursday and return Saturday, a statement from her office said. She and one of her three children will be part of a U.S. delegation that will “visit historic sites” and “learn about Greenlandic heritage.”

On her visit, Vance will attend the Avannaata Qimussersu, Greenland’s national dogsled race, featuring about 37 mushers and 444 dogs. The statement said Vance and the U.S. delegation “are excited to witness this monumental race and celebrate Greenlandic culture and unity.”

Media outlets in Greenland and Denmark reported that Vance would be accompanied by Trump’s national security adviser, Mike Waltz. The White House and the National Security Council did not immediately respond to requests for comment.

Trump had mused during his first term about buying the world’s largest island, even as Denmark, a NATO ally, insisted it wasn’t for sale. The people of Greenland have also firmly rejected Trump’s plans.

Since returning to the White House, Trump has repeatedly said that the U.S. will come to control Greenland while insisting he supports the idea for strategic national security reasons – not with an eye toward American expansionism.