As a result of the 1995 sarin gas attack on a Tokyo subway and the growing concern about a terrorist chemical attack , the U.S. Congress passed laws to implement a program to train civilian agencies on responding to incidents involving Weapons of Mass Destruction ( WMD ) . In response , the U.S. Army Reserve Command 's Homeland Defense Office , then under the direction of LTC Jon M. Byrom , US Army Reserve developed an annual exercise to integrate collective training with specialized HAZMAT protection and decontamination equipment for Army Reserve units with this homeland defense mission . This annual exercise began in 2004 when the 472d Chemical Battalion , under the command of Lieutenant Colonel Scott S. Haraburda , was selected to provide operational command and control over nearly 400 Chemical , Biological , Radiological , Nuclear and high - yield Explosives ( CBRNE ) defense soldiers . The following year , the exercise doubled in size to 800 . In 2006 , the 464th Chemical Brigade commanded this exercise , again under newly promoted Colonel Haraburda as the brigade commander , commanding over 1,100 chemical , military police , and medical soldiers , laying the groundwork for future training efforts with non-military organizations as part of the Defense Support of Civil Authorities for large-scale chemical defense missions . This exercise eventually grew to over 3,000 soldiers with ten civilian hospitals in 2009 and to include foreign contributions with Canadian soldiers in 2014
sarin gas attack on a Tokyo subway
Tokyo subway sarin attack
Operation Red Dragon (civil defense exercise)