White phosphorus leak at US Osan Air Base in South Korea prompts brief evacuation

On July 28, 2026, a white phosphorus leak occurred at the U.S. Osan Air Base south of Seoul, South Korea, prompting South Korean authorities to order brief neighborhood evacuations. The leak resulted from a ground mishap involving munitions, according to a base spokesperson. No casualties were reported, and the evacuation notice was lifted after about 30 minutes as South Korean fire authorities and U.S. forces conducted decontamination. The base established a 1,000-foot safety cordon as a precaution. White phosphorus is a highly toxic substance that ignites on contact with air and is used in smoke screens and incendiary weapons. The incident is under assessment.