WASHINGTON — President Donald Trump said Friday that he could impose tariffs on countries that don’t accept his goal of having the U.S. take control of Greenland.

“I may do that for Greenland, too,” Trump said during a White House roundtable on rural health care after discussing his tariff policies. “I may put a tariff on countries if they don’t go along with Greenland, because we need Greenland for national security.”

The president didn’t elaborate further, including which countries he could target. U.S. tariffs imposed on European Union exports are currently capped at 15%. The E.U. is America’s largest trading partner and largest source of imports.

During the event, Trump also referred to the Supreme Court case on tariffs that the justices haven’t yet ruled on. The president said if the high court doesn’t rule in the administration’s favor, “It’d be a shame for our country.”

A bipartisan congressional delegation held a series of meetings late this week with the leaders of Denmark and Greenland in Copenhagen to discuss the president’s efforts to acquire the Arctic island.

Officials from Greenland and Denmark, which controls the semi-autonomous territory, as well as a host of major U.S. allies, have rejected Trump’s push. Troops from a slew of major European countries, including major U.S. allies, have arrived in Greenland in recent days.

Trump has intensified his threats to take control of the island in recent weeks, arguing that it’s necessary for U.S. national security as American adversaries have built up their presence in the Arctic and as the Trump administration develops its “Golden Dome” defense system.

“We really need it,” the president said Wednesday. “If we don’t go in, Russia is going to go in, and China is going to go in. And there’s not a thing that Denmark can do about it, but we can do everything.”

Trump hasn’t ruled out military action to take control of Greenland, though he said earlier this week that it would be easier to do so through diplomatic efforts. “But one way or the other, we’re going to have Greenland,” he said.

Another option could be for the U.S. to purchase Greenland, which could cost as much as $700 billion, according to three people familiar with the cost estimate, NBC News reported Wednesday.

Danish Foreign Minister Lars Løkke Rasmussen and Greenland’s minister of foreign affairs and research, Vivian Motzfeldt, met in Washington this week with Vice President JD Vance and Secretary of State Marco Rubio.

Rasmussen told reporters afterward that there were no breakthroughs but that the two sides would continue discussions. “It’s clear that the president has this wish of conquering over Greenland. We made it very, very clear that this is not in the interest of the kingdom,” he said, adding that they agreed to form a high-level working group to meet in a matter of weeks.