But according to foreign policy experts, Danish officials have been baffled by Trump’s threats to resort to military intervention to gain control of Greenland because there’s already a long-standing agreement in place for the U.S. to increase its military presence there. In 1951, the U.S. and Denmark signed a little-known defense agreement allowing the U.S. “to improve and generally to fit the area for military use” in Greenland and “construct, install, maintain, and operate facilities and equipment” there. “This agreement is very generous, it’s very open,” Mikkel Runge Olesen, a senior researcher at the Danish Institute for International Studies in...