President Donald Trump started his second term with his sights set on Greenland.

When Trump first proposed buying the Arctic nation during his first administration, it was treated like a joke. But in a phone call last week with Denmark’s prime minister, who controls the autonomous territory’s foreign policy, the president doubled down on his efforts to seize power. In the “aggressive and confrontational” conversation, Trump threatened tariffs if he didn’t get his way. In a news conference earlier this month, he also refused to rule out the use of military force. Now, Denmark is taking him seriously: On Monday, they announced a $2 billion military expansion in the Arctic. 

Though the island is not for sale, the president emphasized Greenland’s importance to U.S. national security. Left unspoken: A U.S. takeover could weaken the country’s mining laws and ban on private property, aiding Trump donors’ plans to profit from the island’s mineral deposits and build a libertarian techno-city.

Trump, who has summarized his own natural resources policy as “drill, baby, drill,” would likely approach the island’s natural resources quite differently from Greenland’s current government, which has opposed large extractive projects. 

In 2019, Trump’s ambassador to Denmark and Greenland visited a major rare-earth mining project on the island shortly before Trump’s first calls to buy the country. Opposition to the mine ushered liberal political party Inuit Ataqatigiit into power two years later, which halted the mine and banned all future oil development.