The CDC, in consultation with other partners in chemical and biological preparedness, have developed a stockpile to respond to biological or chemical terrorism emergencies. To determine and review the composition of the SNS, the CDC considers many factors, such as current biological and/or chemical threats, the availability of medical material, and the ease of dissemination of pharmaceuticals. One of the most significant factors in determining SNS composition, however, is the medical vulnerability of the US civilian population.

SNS assets are stored at strategic locations throughout the US to assure the most rapid response possible. The CDC ensures that the medical material in these SNS storage facilities is rotated and kept within potency shelf life limits.