The US Army built a nuclear-powered city inside the Greenland ice sheet as cover for a plan to run 600 missiles through 4,000 km of tunnels beneath it; Denmark found out in 1997

Camp Century was an underground base in Greenland powered by a nuclear reactor. This base concealed Project Iceworm, a secret plan for 600 missiles. Denmark was not fully informed about the US Army's nuclear missile intentions. The project collapsed due to the glacier's movement and was abandoned. A forgotten soil sample revealed ancient Greenland vegetation, while waste remains a future environmental concern.