U.S. President Donald Trump on Friday signaled a willingness to use force regarding Greenland, disregarding Denmark’s sovereignty over the autonomous Arctic island. Speaking at the White House during a meeting with oil industry executives, Trump said he preferred to reach an agreement on Greenland “the easy way,” but warned that if that failed, the United States would proceed “the hard way.” He described control of the resource-rich island as vital to U.S. national security, citing increased Russian and Chinese military activity in the Arctic.

Trump stated that the United States would not allow Russia or China to take over Greenland, asserting that if Washington did not act, those powers would. His remarks drew surprise from Denmark and other European allies. Danish Prime Minister Mette Frederiksen cautioned that any aggression in Greenland would end “everything,” including NATO and the post–World War II security framework.

U.S. Secretary of State Marco Rubio is scheduled to meet next week with Denmark’s foreign minister and Greenlandic representatives to discuss the issue.