U-S military dependants in South Korea have been attending obligatory classes on chemical and biological warfare and how to wear a gas mask.
The class reflects growing concern about the germ warfare capabilities of neighboring communist North Korea.
Seoul's Defense Ministry says North Korea has boosted its stockpile of chemical weapons fivefold over the past dozen years, to 5,000 tons.
18 people on Friday went through a mandatory two and a half hour class for all U-S military dependants in South Korea.
They listened intently as an instructor explained how to put on a gas mask.
Friday's class took place in the 8th Army's Dragon Hill Lodge hotel in an informal atmosphere.
The trainees, most of them civilian employees of the hotel, first watched a video presentation.
Then instructors gave practical demonstrations on how to use a gas mask, right down to the practicalities of eating or drinking while wearing one.
The U.S. military began distributing standard army gas masks in December to all family members of the 37-thousand U-S soldiers in South Korea.
South Korea is the first place the army is taking the initiative because of North Korea's chemical and biological weapons capabilities.
The U-S initiative attracted civil defence officials, especially in Seoul, 35 miles (55 kilometers) south of the border and well within the range of North Korean missiles and artillery shells that experts say can carry anthrax and other deadly germ weapons.
North Korea has boosted its stockpile of chemical weapons fivefold over the past dozen years, to 5,000 tons, according to Seoul's Defence Ministry.
It is also believed to have stockpiled anthrax and nine other types of biological weapons, and made dramatic strides in its ballistic missile capability.