The United States, not Denmark, should control Greenland, U.S. President Donald Trump said on the sidelines of the NATO summit in Ankara, Turkey, threatening to “remove” U.S. troops in Europe.

“Greenland doesn’t help Denmark. Denmark doesn’t spend money to really help Greenland, but it’s an important part for the United States,” Trump said during a bilateral meeting with Turkish President Recep Tayyip Erdoğan.

The island was “surrounded by China ships and Russian ships,” Trump said, adding that Greenland “should be controlled by the United States, not by Denmark.”

“We could remove all of our soldiers out of Europe,” he added.

Trump’s assertions that the U.S. must acquire or control Greenland, a semi-autonomous Danish territory, have long strained relations between Washington and Copenhagen — both founding NATO members — and, more broadly, U.S. ties with Europe. The issue has since moved to a diplomatic track.

The diplomatic standoff over Greenland escalated in December, when Trump said the U.S. “has to have” Greenland for “national security.”

Tensions rose further in January during the World Economic Summit in Davos in January, when NATO allies, including Canada, expressed solidarity with Greenland and Denmark.

When asked by a reporter how far he would go to acquire Greenland, Trump said, “You’ll find out.”

However, during his speech at the World Economic Forum, he ruled out the use of force.

Hours later, also speaking in Ankara, Danish Prime Minister Mette Frederiksen said she expected allies to respect the sovereignty of the Danish kingdom and accept that Greenland was not for sale.

“It is a well-known position of the United States that it wants to own and take over Greenland. I hope that it is equally well-known everywhere that this is not going to happen,” Frederiksen said.

She added that there were no plans to discuss issues concerning the High North, the Arctic or Greenland while in Akara.

Greenland’s Foreign Minister Mute Egede said in a post on Facebook that Greenland’s future should be decided by its people.

“That’s how it has always been. And that’s how it always will be,” he said, adding that Greenland should continue close co-operation with its allies.

Trump said the issue of control over Greenland had harmed U.S. ties with NATO.

“That’s what hurt my relationship with NATO,” he said.

“They (Denmark) wouldn’t go along with it, and with all the money we spend to help them with Russia.”

U.S. Secretary of State Marco Rubio said in June that conversations with Denmark and Greenland were continuing on a monthly basis.

–With files from The Canadian Press