
A daring but ultimately failed Cold War operation by the CIA to spy on China resulted in a nuclear device being lost on Nanda Devi, one of India’s highest peaks, over 60 years ago. In 1965, a joint team of American and Indian climbers embarked on a secret mission, carrying a plutonium-powered generator intended to serve as a sophisticated surveillance antenna targeting Chinese missile tests. The urgency stemmed from China’s recent nuclear advancements, prompting the CIA to seek advanced intelligence-gathering capabilities.
The mission, code-named the Sikkim Scientific Expedition, was meticulously planned, with Barry Bishop leading recruitment and establishing a plausible cover for the operation. Jim McCarthy, an American climber, was among those recruited for this high-stakes national security assignment. India’s participation was motivated by the persistent security concerns following the 1962 war with China, though some, like expedition leader Captain MS Kohli, harbored significant doubts about the plan’s viability.
During the ascent, a catastrophic blizzard struck the team near the summit. Faced with immediate peril, Captain Kohli made the difficult decision to abandon the sensitive equipment, including the 13-kilogram SNAP-19C generator containing a significant amount of plutonium. The device was left on an icy ledge, with the instruction to secure it rather than attempt a dangerous descent.
The following year, an expedition returned to retrieve the lost device, only to discover that an avalanche had completely obliterated the ledge where it had been left. This devastating outcome confirmed the worst fears of the CIA officers involved, who recognized the grave implications of a lost plutonium source in the Himalayas. Extensive search efforts using radiation and infrared detectors yielded no results.
Jim McCarthy, recalling the device’s heat-generating properties, speculated that it likely melted the surrounding ice and sank further into the mountain. The story of the lost nuclear device remained a closely guarded secret until 1978, when it was brought to public attention. Decades later, the incident serves as a cautionary tale about the risks associated with covert operations and the potential long-term environmental consequences of leaving hazardous materials in fragile ecosystems.







