20. Operation Popeye
One idea concocted by the American military and the CIA involved seeding clouds to make them, literally, rain on the parades of anti-Diem protestors. The hope was that the downpour would dampen turnout and disperse the crowds. That did not save Diem, who was overthrown and assassinated in 1963. However, the idea of seeding clouds seeding survived to be used as a tactic in the Vietnam War. Codenamed Operation Popeye, modified cargo planes began flying over the Ho Chi Minh Trail in 1967, releasing silver and lead iodide flares.
The idea was to heavily increase the monsoon period’s rainfall, and thus negatively impact the routes used to supply and reinforce communist forces in South Vietnam. By the time Operation Popeye was terminated in 1972, over 2600 missions had been flown, during which roughly 47,000 cloud seeding charges were dropped. Their impact on the Ho Chi Minh trail and communist supplies and reinforcements were next to nil.