South Koreans wear gas masks during a civil defense drill simulating a North Korean attack near the border city of Paju, South Korea, on Wednesday, Dec. 15, 2010. (AP Photo/Lee Jin-man)

Photo by: Lee Jin-man

South Koreans wear gas masks during a civil defense drill simulating a North Korean attack near the border city of Paju, South Korea, on Wednesday, Dec. 15, 2010. (AP Photo/Lee Jin-man)