It was called Project Iceworm, inspired by Norwegian-born US Army colonel Bernt Balchen, who pushed for the US military's continued presence in Greenland as a strategic geographical midway point between the US and the Soviet Union.
The US Army had planned on digging trenches under Greenland's ice, in which they will burrow medium-range ballistic missiles (MRBMs) as a means of deterring the Soviet Union from targeting the US. They had also wanted to build an underground city where they will presumably conduct operations undetected by Soviet satellites.
However, what foiled the US Army's plans was neither Soviet spies or budget constraints. It was nature, as Greenland's ice started to shift. After nine years of building the facility that was supposed to house 600 MRBMs, they were forced to abandon the site, which cost an estimated $2.37 billion.
However, this also led to some tension between Denmark and the US after the truth was exposed. Thankfully, the discovery of fossilized leaf and twig fragments under the ice helped ease those tensions as it suggested that there had been plants growing there before.
(Image credit: Tina Rolf/Unsplash)