How an India-US spy mission lost a nuclear device in the Himalayas

India Today

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In February 2021, devastating flash floods struck Uttarakhand, killing around 80 people, leaving 124 missing, and completely wiping out two hydropower projects. A theory resurfaced that a lost nuclear-powered surveillance device, abandoned at 25,000 feet in the Himalayas in 1965 during a joint US-India expedition to Nanda Devi, might have contributed to the disaster by melting snow and triggering avalanches. But that, thankfully, was not the case.advertisementScientific investigations identified a different cause: a massive rock and ice avalanche, triggered by the collapse of a hanging glacier near Ronti Peak. The sheer force of the falling mass generated enough heat and momentum to release a deadly surge of water, debris, and silt down the Rishiganga and Dhauliganga rivers, resulting in the sudden catastrophic floods.The lost nuclear device from the Nanda Devi Plutonium Mission has returned to public discourse with every natural calamity in Uttarakhand, be it the 2021 disaster or the 2018 cloudburst, or the more recent incident of Joshimath's subsidence.
The device was reportedly a listening device to keep tabs on China's nuclear programme being installed in the high Himalayas by India and the US. It was a covert operation of the Central Intelligence Agency (CIA) of the US and the Intelligence Bureau (IB) of India, according to reports.There's also a theory that the device, which was lost in a blizzard in 1965, was later retrieved by India for reverse-engineering purposes.Now, decades later in 2025, nuclear anxieties are surging once again. First, a radiation scare in Pakistan's Kirana Hills, then missile strikes on Iran's nuclear sites, brought back anxieties about the risks of nuclear radiation.In May, reports of a radiation leak at Pakistan's Kirana Hills, a suspected nuclear storage site, sparked concern, but the International Atomic Energy Agency (IAEA) confirmed no radiation leak had occurred. Subsequently, US missile strikes on Iran's nuclear facilities at Fordo, Isfahan, and Natanz in June raised fears of radiological leaks, though there was no evidence of that.The story of the long-buried 1965 plutonium mission to Nanda Devi has regained relevance and interest against this backdrop.Thus, it's an opportune moment to revisit why India partnered with the CIA during the Cold War; why a nuclear-powered surveillance device was carried into the icy heights of the Himalayas; how the CIA and India's Indo-Tibetan Border Police (ITBP) collaborated and tried to deploy the thermonuclear generator device, codenamed "Guru Rinpoche", there; how it got lost, and why, even today, that lost device continues to cast a radioactive shadow over the region.advertisementAdding to the mystery, a year later, when a recovery team went back to locate the device, they found it had vanished from the area.INDIA'S EVEREST TRIUMPH AND BACKDOOR CIA TIESThe story began not with espionage, but with adventure.In May 1965, a team of Indian mountaineers, led by Navy officer Captain Mohan Singh Kohli, became the first Indian team to successfully scale Mount Everest.Kohli, who had been inducted into the ITBP for his mountaineering skills, returned home a hero. In June, the team led by Kohli was welcomed in New Delhi by ministers, military brass, and intelligence officers."Immediately after the return of the 1965 Indian Everest Expedition to New Delhi on 23 June, I was asked to lead a covert Himalayan expedition to Nanda Devi involving leading mountaineers, intelligence officials, nuclear scientists and daredevil pilots, drawn from both the USA and India," Mohan Singh Kohli noted in his 2003 book, 'Sherpas, the Himalayan Legends'.
Captain Mohan Singh Kohli (retd) (L), a distinguished officer of the Indian Navy and a renowned mountaineer, led India's first Indian Everest Expedition in 1965. The summit saw nine climbers conquer the summit, setting a world record that remained unbeaten for 13 years. (Images: PIB/IndiaPost)
advertisementOne among them was Balbir Singh, a senior intelligence official, who quietly pulled Kohli aside and introduced him to RN Kao, then a low-profile officer but a razor-sharp chief of the Aviation Research Centre (ARC), the elite wing under India's Intelligence Bureau (IB).Kao, who would go on to found RAW (Research and Analysis Wing), was then heading India's covert aerial reconnaissance programme. Kohli was told he would soon travel to the United States. No explanation was given. He didn't even have a passport, but one had already been arranged, Kohli was told.What Kohli didn't know then was that he was about to be roped into a secret CIA-ARC collaboration, one that combined mountaineering and espionage.WHEN HIMALAYAS BECAME SPY CENTRE; COLD WAR AT 25,000 FEETIn 1964, Communist China detonated its first nuclear bomb in Lop Nur, Xinjiang.This rattled both the Capitalist United States and China's neighbour, India.Satellite surveillance was still rudimentary, and the Americans were desperate for closer access to seismic and radiological data from China's nuclear test sites. India's newly forged friendship with the US provided an opportunity.advertisementThe plan: install a radioisotope thermoelectric generator (RTG), codenamed "Guru Rinpoche", on a Himalayan ridge near the Nanda Devi peak (7,817 metres/ 25,646 feet), close to the Tibetan border.Since there was no source of electricity at that height, it was planned that the RTG would power a listening device to detect and transmit signals from China's nuclear experiments. Heat signatures, seismic waves, and radiation levels from China were to be collected and documented.Unlike traditional batteries, the RTG was designed to operate without maintenance for years, with a core of Plutonium-238, which was highly radioactive.The RTG and the surveillance equipment weighed over 50 kilograms. Lugging it up the icy slopes of the Himalayas would take dozens of men.Soon, a team comprising ITBP mountaineers, American operatives, and, most importantly, Sherpas was assembled to haul it up one of the world's most treacherous routes and place it on a ridge close to the peak.
China's first successful atomic bomb explosion, in 1964, spooked both the US and India. (Image: People's Pictorial, January 1965 issue)
advertisementHOW BLIZZARD STOPPED CIA-IB'S NUCLEAR CLIMB TO NANDA DEVIBy mid-September 1965, Kohli and the joint CIA-ITBP team started the mission to carry the device up Nanda Devi and reached the base camp.Despite the unpredictable weather, the team pushed ahead, and set up a series of several stocked-up camps along the ascent route.It was planned that a team of Sherpas would first ferry the heavy surveillance equipment from Camp IV to a suitable point near the summit. Once that was done, a second team, comprising two Indian and two American climbers, would climb up, and assemble the nuclear-powered device in a secure position and crank it up.But by October 16, when the mission reached Camp IV with the nuclear device, nature had other plans. A severe blizzard rolled in.Blizzards and the threat of avalanches made progress impossible. Kohli reluctantly made the call to abort.With visibility dropping and safety at stake, the team anchored the device securely into a crevice, hoping to retrieve and install it once conditions improved. They lashed the RTG to a rock at Camp IV, planning to return after the winter thaw, noted Kohli in his 2003 book.The weather conditions and the remote location, however, allowed no further movement that season. The climbers descended, leaving behind not just their cargo, but the first signs of a future mystery.
A view of the Nanda Devi and its sibling peaks from Uttarakhand's Nainital. (Image: Unsplash)
HOW NUCLEAR DEVICE DISAPPEARED IN HIMALAYAS WITHOUT A TRACEWhen the recovery team returned in 1966, the device was gone.Indian mountaineer GS Bhangu, who also assented the Everest and the covert Nanda Devi expedition in 1965 along with Kohli, led the expedition with six Sherpas."Bhangu rushed to the rock with which he had secured the equipment in 1965. The rock ledge had broken down! There was no sign of the nuclear-powered generator. For a moment, Bhangu stood stunned and motionless. He frantically looked around. During the winter, tons of fresh snow must have fallen on Nanda Devi. Under its weight the device must have broken off the rock-ledge and gone down. To where?," noted Kohli in his book.The rock it had been tied to had disappeared. A snowstorm or avalanche had likely swept it away."The Nanda Devi slopes were soon scoured by climbers and Sherpas trying to locate the abandoned device. The Sherpas had never been used for such work. They took it in their stride and went about this new task with great sincerity. After several days of strenuous work, they all drew a blank," wrote Kohli.It was a high-risk failure and a big setback. The disappearance of a nuclear device in one of the world's most ecologically sensitive and densely populated watersheds triggered alarm in both Washington and New Delhi.NO TRACE OF NANDA DEVI N-DEVICE DESPITE SEARCH OPsThe CIA and Indian intelligence scrambled.For two years, search missions combed the mountain, hoping to locate the RTG before it ruptured or slid further into the valley. But Nanda Devi, 25,643 feet tall and often shrouded in ice storms, revealed nothing.In internal reports, the CIA acknowledged the loss of the plutonium-powered device. The Indian government, fearing public outrage and scrutiny, never officially admitted its role in the operation until decades later.No radiation leak has ever been confirmed.A 1978 Indian Atomic Energy Commission survey found no plutonium traces in the region, but also could not locate the device.In 1967, two years after the Nanda Devi mission was aborted, a similar device was successfully installed on nearby Nanda Kot, a lower and less treacherous peak. That surveillance post functioned for a few months, gathering intelligence before its electronics failed. Eventually, the US transitioned to non-nuclear, solar-powered devices and later, more sophisticated satellite systems.The CIA-India nuclear mission was quietly buried under official secrecy, until it was publicly acknowledged by Kohli, and reported in the Indian and American press in the 1990s and early 2000s.
A map marking Nanda Kot, the peak where a nuclear-powered surveillance device was eventually installed in 1967 after the attempt to do that at Nanda Devi failed in 1965. (Image: CIA Archive)
In 1978, when the issue reached Prime Minister Morarji Desai, after questions were raised in the US, he was compelled to respond publicly by appointing a high-level scientific committee to investigate the matter, assess potential environmental dangers, and recommend steps to locate the missing nuclear device and prevent future hazards.However, American author Broughton Coburn, in his book 'The Vast Unknown: America's First Ascent of Everest', claimed that members of Indian intelligence agencies might have secretly trekked up the Nanda Devi route before the official spring recovery mission and retrieved the device, possibly to study its design or extract the plutonium without informing the Americans.Though over half a century has passed, the spectre of the Nanda Devi device has never quite disappeared.Environmentalists and scientists continue to express concerns over radioactive contamination if the RTG were to rupture due to geological tectonic shifts or glacial melting.Today, as the world confronts fresh nuclear threats, from Iran to Pakistan, the missing nuclear device on Nanda Devi, which is likely buried under snow, but resurfaces regularly in the minds of people. It is an unsolved mystery that keeps spooking people.- Ends