A recently published investigation by The New York Times has brought renewed attention to one of the Cold War's most troubling legacies: a plutonium-powered nuclear generator lost on a Himalayan peak 60 years ago that has never been recovered.

The device, containing nearly a third of the plutonium used in the Nagasaki bomb, disappeared during a covert 1965 CIA-Indian Intelligence Bureau mission to spy on China's nuclear program. The investigation, released December 13, details how the SNAP-19C portable generator vanished from Nanda Devi, India's second-highest peak, after climbers were forced to abandon it during a fierce blizzard.

A Cold War Operation Gone Wrong

In October 1965, a team of American and Indian mountaineers attempted to install nuclear-powered surveillance equipment on the 25,645-foot summit to intercept telemetry from Chinese missile tests. Captain M.S. Kohli, who led the expedition, recalled warning officials that the mission would be "if not impossible, extremely difficult," but the operation proceeded.

On October 16, 1965, climbers ascending the southwestern ridge encountered brutal conditions. "We were 99 per cent dead," recalled Sonam Wangyal, an Indian intelligence officer on the mountain. "We had empty stomachs, no water, no food, and we were totally exhausted". Kohli ordered the team to secure the generator to an ice ledge and retreat.

When a recovery expedition returned in May 1966, the entire ice shelf had vanished, likely swept away by an avalanche. Multiple subsequent searches using radiation detectors and metal scanners failed to locate the device.

Ongoing Environmental and Security Concerns

The missing device continues to raise alarms in India. While scientists say contamination of the Ganges River would likely be diluted by water volume, concerns remain for communities near mountain streams fed by glaciers from Nanda Devi. Plutonium is highly toxic if inhaled or ingested and is known to cause cancer.

Following a 2021 landslide near Nanda Devi that killed more than 200 people, speculation resurfaced about whether heat from the missing generator could have played a role, though scientists point to climate change as the likely cause. Indian MP Nishikant Dubey has called on Washington to take responsibility: "Who owns that device should take out that device".

Both the U.S. and Indian governments continue to refuse comment on the operation, citing policy on intelligence matters. The CIA has never publicly acknowledged the mission. Captain Kohli, who passed away in June 2025 at age 93, spent decades advocating for the device's recovery.