Sergeant Ryan T. Sotelo, section leader, Weapons Company, Battalion Landing Team 3/5, 15th Marine Expeditionary Unit, listens during a class on chemical, biological, radiological and nuclear defense, aboard the USS Peleliu, Oct. 4. The 15th MEU's CBRN Defense Platoon is spending an entire month preparing the 2,400 servicemembers that make up the MEU on how to properly operate in contaminated environments. The 15th MEU is currently embarked as part of the Peleliu Amphibious Ready Group, while they serve as the nation's rapid-response sea-based Marine Air Ground Task Force for Western Pacific Deployment 12-02. Sotelo, 30, is from San Mateo, Calif.