After World War II, Denmark turned down an offer of $100,000,000 from the United States to buy Greenland.

Post World War II, the United States became interested in Greenland, due its closer proximity to Europe. The looming threat of a war with the USSR was just beginning and the Cold War with it. 

In the hope of gaining a better foothold in Europe with which to establish closer missile defense, in 1946, the US offered to buy Greenland from Denmark for $100,000,000, but Denmark refused. In 1950, however, Denmark allowed the United States to establish the Thule Air Base, as part of a NATO Cold War defense strategy. So in the end, the US accomplished their general goal. 

(Source)