Without adequate protection, technologies and materials—from clothing to electronics to binoculars—rapidly deteriorated in tropical environments. While tropical decay may seem a trivial issue today, it posed a serious logistical and strategic problem that prompted the U.S. military to develop a program of environmental testing beginning during World War II to ensure equipment reliability in these harsh conditions. Tracing that history of environmental testing through the Vietnam War, this article argues that the military's management of tropical rot operated through the spatial logic of climatic analogs, where simulated sites on U.S.-controlled soil stood in for battlefields across the global tropics. However, because climatic analogy was never perfect, the environmental testing program needed continual calibration to adjust to sites of “hot” conflicts during the Cold War. While the Panama Canal Zone initially served as a proxy site for the Pacific during World War II, scientific experts cast doubt on its similarity to the Southeast Asian tropics as American involvement in Indochina loomed. To strengthen their environmental testing, they collected environmental data from a site in U.S.-allied Thailand as a proxy for Indochinese environments. In uncovering an overlooked dimension to the U.S. empire's environmental history, this article demonstrates not only how weatherability and environmental testing provided an important, yet hidden infrastructure for the global projection of American power, but also how establishing and calibrating climatic analogs drove the production of environmental knowledge about the tropics. Placing the U.S. military's tropical science against the legacy of colonial discourse on the tropics, this article complicates usual portrayals of the military's environmental ignorance and instead highlights the ambivalent role of military-sponsored tropical decay research in shaping the U.S. empire's relationship to the natural world.
Boyd Ruamcharoen (2026) studied this question.