At the height of the Cold War in the 1950s, the Greenland ice sheet hosted a number of clandestine U.S. Army bases whose job it was to get an estimated 600 medium-range ballistic missiles with nuclear warheads ready for deployment. The largest of these sites was Camp Century, which had the public facade of a science station.
The Army never finished what it started at Camp Century. It abandoned the base in 1967, scrapping Project Iceworm, as its secret mission was called. But the Army left behind a nasty legacy buried under all that ice and snow — tons of toxic waste that military officials assumed would stay frozen forever.
Source: Climate Change Just Revealed A US Military Secret Once Thought To Be Buried Forever | CleanTechnica