White Phosphorus Leak at US Osan Air Base Triggers Brief Evacuation in Pyeongtaek, South Korea

white phosphorus Osan Air Base Pyeongtaek evacuation US military chemical leak

On July 28, 2026, a leak of white phosphorus was reported at the U.S. 51st Fighter Wing’s Osan Air Base (K‑55) in Pyeongtaek, about 60 km south of Seoul. The incident was detected around 5 p.m. local time. South Korean authorities issued an emergency text alert at 5:37 p.m., ordering nearby residents to move to safe locations and avoid skin exposure. Fire‑engine units (nine) and 31 firefighters were dispatched, and police established a security cordon of roughly 300‑500 m around the base.

The leaked material was described as pre‑diluted white phosphorus, about 80 % diluted, reducing health and environmental risk. No injuries or casualties were reported. The evacuation order was lifted after about 36 minutes, at roughly 6:13 p.m., once decontamination was completed. U.S. forces confirmed the situation was under control, lifted all safety restrictions, and resumed normal operations at the base. Both U.S. and South Korean officials emphasized that the safety of service members, their families, and local residents remained the highest priority.

Entities: K-55 (Osan) Air Base · Osan Air Base · Osan Air Base (K‑55) · Pyeongtaek · Pyeongtaek City · Pyeongtaek city government · Pyeongtaek, South Korea · South Korean authorities · U.S. 51st Fighter Wing · U.S. military · United States 51st Fighter Wing · White phosphorus

Claims

What the coverage asserts, and how well corroborated each claim is across sources.

[● 11 SOURCES] Fire and police deployed nine fire‑engine units and 31 personnel to the site. (supporting_article_ids)
[● 7 SOURCES] Authorities continued to investigate the cause and extent of the leak. (existing)
[● 9 SOURCES] No injuries or casualties were reported. (existing)
[● 5 SOURCES] U.S. military said the leaked white phosphorus had been pre‑diluted about 80 %. (existing)
[● 9 SOURCES] Pyeongtaek city issued an emergency disaster text at 5:37 p.m. ordering nearby residents to evacuate to safe locations. (existing)
[● 9 SOURCES] The evacuation order was lifted around 6:13 p.m., after about 36 minutes. (existing)
[● 6 SOURCES] The leak involved white phosphorus from two ammunition shells; the exact amount was not disclosed. (existing)
[● 9 SOURCES] A leak of white phosphorus was reported at the K‑55 (Osan) U.S. military base in Pyeongtaek on July 28, 2026 at 5:07 p.m. (existing)