The Antarctic environment is one which provides information on the difficult task of living in a contained environment. The ability to sustain oneself in small group operations with little contact with the outside for various periods of time is critical to the operations of contained, protected environments such as the Survivable Collective Protection System (SCPS) in a chemical and biological warfare (CBW) environment. The provision of medical care following the nuclear disaster at Chernobyl is presented in this volume, providing information concerning the stresses and coping strategies after toxic exposure. The ways in which threats are perceived and the experience of risk is mediated through group values, culture, and symbols. Risk perception is an inherent aspect of the CBM experience of threat, fear, and terror, one which will influence leaders and troops alike. Acute stress reactions to conventional and CBW military threat, particularly classical forms such as combat stress reaction (CSR) and post-traumatic stress disorder (PTSD), are discussed with regard to the psychiatric treatment roles of the medic, the medical aid station, the field hospital and the rear echelon hospital. Lastly, the broad areas of responses to disasters and the development of psychiatric symptoms and the lack of symptoms in communities exposed to tragedies and disasters are examined.