President-elect Donald Trump Tuesday threatened to place new tariffs on imports from Denmark unless the country gives up control of Greenland, news that dented the stocks of some of Denmark’s most important companies and underscored Trump’s focus on geopolitical competition.

On March 30, 1867, U.S. Secretary of State William H. Seward and Russian envoy Baron Edouard de Stoeckl signed the Treaty of Cession. With a stroke of a pen, Tsar Alexander II had ceded Alaska, his country’s last remaining foothold in North America, to the United States for US$7.2 million.

Interest in the vast, ice-covered island reflects global scramble for the Arctic.