US soldiers inspect vehicles at Camp Humphreys in Pyeongtaek, Gyeonggi Province, during a joint Korea-US military exercise in March. [Newsis]
US soldiers inspect vehicles at Camp Humphreys in Pyeongtaek, Gyeonggi Province, during a joint Korea-US military exercise in March. [Newsis]

A white phosphorus leak reported at a US military base in Pyeongtaek, Gyeonggi Province, prompted a brief evacuation order for nearby residents Tuesday afternoon before authorities lifted it about 36 minutes later.

According to Yonhap, an official at Osan Air Base (K-55), a USFK installation in Seotan-myeon, Pyeongtaek, notified South Korean police of the leak at 5:07 p.m.

White phosphorus is used as a smoke-producing filler in artillery shells and has incendiary properties. It is considered highly dangerous because it can burn through human skin until combustion is complete, and the international community has recommended banning its use.

US forces detected the leak during a routine missile inspection, finding that oxygen levels inside a warhead had fallen outside the acceptable range and that an unidentified liquid had pooled at the warhead's base.

At the base's request, Pyeongtaek city sent an emergency text message at 5:37 p.m. — 30 minutes after the initial report — reading: "(Evacuation order) White phosphorus leak inside K-55 US military base. Nearby residents are advised to evacuate to a safe location to avoid skin exposure."

Around the same time, fire department authorities mobilized nine vehicles and 31 personnel to respond at the scene alongside the US military's Explosive Ordnance Disposal unit. Police also deployed patrol cars 300 to 500 meters from the base to block civilian access and redirect vehicle traffic.

During an on-site assessment, US military police determined that "the white phosphorus leak point is more than 300 meters from the base perimeter fence, making it unlikely that the substance would spread outside the installation or affect South Korean residents."

US forces also noted that the leaked white phosphorus had been pre-diluted to approximately 80 percent, reducing the risk to human health and the surrounding environment, and relayed this information to Pyeongtaek city.

The National Institute of Chemical Safety also concluded that evacuation was unnecessary, as no residential buildings stood within a 300-meter radius of the leak site.

Pyeongtaek city then sent a second emergency text message at 6:13 p.m. — 36 minutes after issuing the evacuation order — stating: "(Evacuation order lifted) The white phosphorus leak inside K-55 US military base has been contained. Nearby residents may return to their daily routines."

Fire department personnel wrapped up their response operations with US military counterparts at around 6:50 p.m. and withdrew from the scene. Police also pulled back the officers deployed for traffic control at around the same time.

A police official said the US military had informed them that "a chemical used to clean warheads leaked inside the K-55 ammunition depot, but there is currently no danger."

The evacuation order was ultimately deemed unnecessary given how far the leak site was from the base perimeter, but US forces misjudged the distance and triggered the order — leavingresidents near the base anxious for a time.

USFK issued a press release disclosing the incident and the response measures taken at around 7:42 p.m., two hours and 35 minutes after the initial report.

USFK said its on-base emergency response team had established a safety perimeter of about 300 meters around the site and was working to resolve the situation, adding that it was "handling the matter as quickly and safely as possible."


ehkim@heraldcorp.com