CIA’s Lost Nuclear Device On Nanda Devi; A Cold War Secret From 50 Years Ago

Last Updated:December 15, 2025, 16:37 IST

In 1965, a CIA-India mission left a plutonium-powered device on Nanda Devi to spy on China. Lost in a blizzard, its fate remains unknown, sparking fears of radioactive fallout.

In 1965, a CIA-India mission left a plutonium-powered device on Nanda Devi to spy on China. Lost in a blizzard, its fate remains unknown, sparking fears of radioactive fallout. (Image: Flickr)

At the height of the Cold War in 1965, just months after China detonated its first atomic bomb, a secret joint mission between the United States and India unfolded high in the Himalayas, one that would leave behind a nuclear-powered device buried under ice, never to be recovered, reported by The New York Times

The objective was espionage. The Central Intelligence Agency (CIA) wanted to monitor Chinese missile tests by intercepting radio signals from deep inside theTibet and Xinjiang regions. For that, it needed altitude and secrecy. The chosen location was Nanda Devi, one of India’s highest and most forbidding peaks, overlooking the Chinese border.

Disguised as a scientific expedition, a team of elite American and Indian climbers carried surveillance equipment up the mountain. Among the cargo was a SNAP-19C generator, a portable nuclear-powered device weighing around 50 pounds and fuelled by highly radioactive plutonium similar to the technology used later in space missions like Voyager.

Inside the generator were plutonium capsules containing nearly a third of the amount used in the Nagasaki bomb.

As the climbers prepared for their final ascent in October 1965, disaster struck. A violent blizzard engulfed the mountain, cutting off visibility and trapping climbers near the summit. From the advance base camp below, Captain MS Kohli, the Indian naval officer leading the mission, feared for their life.

“Come back quickly. Don’t waste a single minute," Kohli radioed the team.

In a decision that would have lasting consequences, he ordered the climbers to secure the equipment and abandon it near Camp Four rather than risk carrying it down in lethal conditions.

The climbers came downhill, and the nuclear device was left behind.

When the team returned the following year to retrieve it, the entire ice ledge, equipment, cables, and generator were gone, as an avalanche had torn it away.

Despite repeated search missions using radiation detectors, infrared sensors and metal scanners, the device was never found.

The United States never publicly acknowledged the operation. Officially, nothing had happened.

The origins of the mission were almost surreal. According to later accounts, the idea was born at a cocktail party where US Air Force General Curtis LeMay spoke with Barry Bishop, a National Geographic photographer and famed Everest climber. Bishop described how Himalayan peaks offered sweeping views into Chinese territory.

Soon after, the CIA recruited Bishop to organise a covert expedition under the cover of scientific research. He set up the “Sikkim Scientific Expedition," recruited climbers, prepared false documentation, and kept the true purpose secret.

India quietly joined the mission, driven by fears of China after the humiliating 1962 border war. But even then, Kohli was sceptical.

“It was nonsense," he later said.

When the CIA initially proposed installing the device on Kanchenjunga, the world’s third-highest peak, Kohli bluntly objected. “Whoever is advising the CIA is a stupid man," he said.

Eventually, Nanda Devi was chosen.

The climbers were rushed to high altitude with little acclimatisation. Many fell ill. Ironically, the plutonium generator gave off heat, making it desirable to carry. Sherpas fought over who got to handle it.

“At the time," Kohli said, “we had no idea about the danger."

One of the Indian climbers, Sonam Wangyal, later recalled the blizzard that ended the mission. “We were 99 per cent dead," he said. “No food, no water, totally exhausted."

When Kohli ordered the equipment abandoned, American climber Jim McCarthy protested fiercely. “You’re making a huge mistake," he shouted. But the decision stood.

What followed was silence until 1978.

Journalist Howard Kohn uncovered the story and published it in Outside magazine. The revelations sparked outrage in India. Protesters warned that the CIA was “poisoning our waters," fearing radioactive contamination of glaciers that feed the Ganges, a lifeline for hundreds of millions.

Behind the scenes, the US and Indian governments scrambled to contain the fallout. President Jimmy Carter and Prime Minister Morarji Desai quietly coordinated to prevent diplomatic damage. In a private letter, Carter praised Desai for handling the “Himalayan device problem," calling it an “unfortunate matter."

Publicly, both governments said little.

Scientists say the device cannot explode on its own, but plutonium is highly toxic. As glaciers melt, there are fears the generator could surface, contaminating water or being misused. Some experts warn of the possibility of the plutonium being repurposed into a “dirty bomb" if recovered.

Decades later, the mystery continues to haunt those involved.

What If the Device Resurfaces?

The nuclear-powered generator left on Nanda Devi cannot explode like a bomb, but experts say its resurfacing could still pose risks. The device contains plutonium, which is highly radioactive, and the radiation can cause long-term damage to vital organs.

As Himalayan glaciers melt due to climate change, scientists warn that the generator or its plutonium capsules could emerge from the ice. If damaged, radioactive material could contaminate snowmelt and streams that feed the Ganga River, a critical water source for millions.

Security experts also caution that if recovered by unauthorised actors, the plutonium could be used to make a “dirty bomb" designed to spread radioactive material and trigger panic.

Even accidental discovery by villagers or trekkers could lead to radiation exposure without immediate awareness. While authorities have previously downplayed the risk of large-scale contamination, environmentalists say the unanswered questions around the missing device are becoming increasingly urgent.

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