Greenlanders are seeing red over President Trump's pursuit of the island territory.

Over the weekend, the president announced an imminent 10% tariff on eight European countries for not backing his plan for the U.S. to control Greenland.

The president has said Greenland is vital for U.S. national security.

But now his new threat is angering European allies, who warned the tariffs could set off a "dangerous downward spiral."

"The use of tariffs against allies is completely wrong," said UK Prime Minister Kier Starmer. "A trade war is in no one's interest."

However, some European leaders are reportedly considering just that — by possibly retaliating with tariffs on $107 billion worth of goods.

MORE ON TARIFFS | Europe warns of 'dangerous downward spiral' after Trump threatens tariffs over Greenland

"It's a negative feedback loop that ends up happening is as I increase it, you increase it and then it just goes on and on and on," said Babak Hafezi, adjunct professor of international business at American University.

Americans have felt the pinch of tariffs over the past year, after President Trump levied so-called reciprocal tariffs on trade partners.

"When people talk about the affordability crisis, a source of that, one of the sources of that is the tariffs that are being put in place that are making foreign goods more expensive in the united states," said Michael Klein, professor of international economic affairs at Tufts University.

Those tariffs bumped prices up 5-6.5%, according to a Harvard Business School analysis from last year.

And new tariffs against these European allies could bump the price up of certain goods that U.S. imports from them, including pharmaceuticals, cars, and some wine and food.

"All that is going to be tariffed and all that will increase the prices throughout the supply chain," Hafezi said.