In 1965 the CIA lost something in the Himalayas that is still a threat to 600 million people.
China successfully conducted its first nuclear test in 1964, this caused serious concerns in both the US and India. Facing a common threat, the two countries decided it would be wise to spy on the Chinese from the heights of the Himalayas.
To do this they decided to plant a nuclear powered listening device on top of the second highest peak in India, Nanda Devi.
The device was called SNAP-19C, a radioisotope thermoelectric generator containing 5kgs of weapons grade plutonium. The plan was to conduct surveillance over the Tibetan Plateau and operate for decades with zero maintenance.
A joint team of American and Indian climbers was assembled and the mission went ahead. Everything was going well until they reached 7500 meters, just 300 meters from the summit, when a blizzard struck. To save their lives they had to retreat, leaving the generator anchored to an ice shelf. The plan was to retrieve it in spring.
But when they returned, an avalanche had already swallowed everything. Multiple recovery missions were launched but nothing was ever found.
60 years later, that 5kgs of weapons grade plutonium remains buried beneath the glaciers which are the source of River Ganga. The device is still missing, still radioactive and nobody is looking for it.