Operation Popeye was a covert U.S. military weather modification program carried out during the Vietnam War with the goal of extending the monsoon season over parts of Southeast Asia. By artificially seeding clouds to increase rainfall, the operation aimed to disrupt enemy supply routes, flood roads, and make terrain more difficult to navigate. Kept secret for years, the program only became public after investigative reporting and later confirmation by government officials, raising serious ethical and legal questions about the use of environmental manipulation as a weapon. This episode explores what Operation Popeye was, how it worked, why it remained hidden, and what it reveals about the lengths governments may go to in the pursuit of military advantage.