The Nanda Kot device returned data for several months before failing, and a climbing team recovered it in the summer of 1968.
Notes on verification
Confirmed by multiple independent sources including Wikipedia, The Wire (citing M.S. Kohli's writings), and Live History India. Minor wording variations exist but core facts—device operating for months then failing, retrieval in summer 1968—are consistent across sources. [cascade flags: wikipedia_dropped_other_sources_exist | tier=bronze indep_score=0.525 clusters=2 claim_tier=notable | framework convergence=partial (upstreams: M.S. Kohli's memoir 'Spies in the Himalayas' and his 2012 Indian Police Journal article, declassified CIA-related reporting via Wired/Outside magazine investigations) — publishers independent, evidence may not be | kind=empirical eligibility=high]
Sources
- How the United States Lost a Nuclear Device and Recovered an Indian Friend (seed:military_and_intelligence)
- https://m.thewire.in/article/security/inside-the-nanda-devi-nuclear-spy-mission-what-the-nyt-revisited-and-what-it-missed/amp (corroboration)
- https://www.livehistoryindia.com/story/eras/nanda-devi-nuclear-device (corroboration)