At the height of the Cold War, when the world’s great powers played their deadliest games in the shadows, a covert CIA mission unfolded high in the Indian Himalayas — and ended in a mystery that refuses to fade.
Nearly six decades later, the fate of a plutonium-powered nuclear device lost on one of the world’s tallest mountains remains officially unacknowledged by the United States, even as concerns persist that it could pose long-term environmental and security risks to millions who rely on the Ganges river system, according to a recent New York Times report.
The operation was born out of Cold War paranoia and technological ambition. In the mid-1960s, American and Indian climbers quietly set their sights on Nanda Devi, India’s second-highest peak. Their mission was not just mountaineering glory, but the installation of a nuclear-powered surveillance station designed to spy on China’s growing missile and nuclear programme.
At the heart of the plan was a SNAP-19C generator — a compact but highly radioactive device fuelled by plutonium-239, the same isotope used in the atomic bomb dropped on Nagasaki. The generator was meant to power an antenna capable of intercepting telemetry from Chinese nuclear tests. Similar nuclear batteries were later used by Nasa to power deep-space missions like Voyager I.
But the mountain had other plans.
In 1965, as the climbers pushed toward the summit, a fierce blizzard swept across Nanda Devi. Facing impossible conditions, the expedition leader made a life-or-death call. The team secured the heavy generator — weighing about 50 pounds — near the summit and descended immediately.
When climbers returned the following spring, the device was gone.
An avalanche had ripped away the ledge where the generator had been stored. Search teams were dispatched, sweeping the area with radiation detectors and metal sensors. They found nothing. The plutonium-powered device had vanished into the mountain.
Inside the CIA, alarm bells rang. In Washington and New Delhi, anxiety mounted. What followed was a decades-long effort to bury the truth — an effort that continued across administrations, including during the presidency of Jimmy Carter.
The fear was simple and profound: the generator was believed to be trapped beneath glaciers that feed into the Ganges River, a lifeline for hundreds of millions across northern India. Scientific studies conducted in the 1970s found no evidence of radioactive contamination and concluded the immediate risk was low. Yet the unease never disappeared — especially as climate change accelerates the melting of Himalayan glaciers.
The secret finally surfaced in 1978, when an investigative journalist exposed the mission. The revelation sparked outrage across India. Lawmakers accused their government of allowing the CIA to operate covertly on Indian soil, while protesters warned that a foreign intelligence agency had endangered the headwaters of India’s most sacred river.
Declassified diplomatic cables later revealed how President Carter and then–Indian prime minister Morarji Desai quietly worked behind the scenes to manage the fallout and prevent the issue from spiralling into a diplomatic crisis.
Today, the mystery still hangs over Nanda Devi like a shadow frozen in ice. Indian politicians, environmentalists, and villagers living near the mountain have renewed calls for the device to be located and removed. Some worry that a warming climate could eventually expose the generator. Others fear the consequences if its radioactive material is ever discovered — or misused.
High above the plains, buried somewhere beneath ice and rock, the relic of a Cold War gamble remains lost — a silent reminder that even the most secret missions can leave scars that last for generations.