[en] A major mission of safeguards is to protect against the use of nuclear materials by adversaries to harm society. A hierarchical structure of safeguards responsibilities and activities to assist in this mission is defined. The structure begins with the definition of international or multi-national safeguards and continues through domestic, regional, and facility safeguards. The facility safeguards is decomposed into physical protection and material control responsibilities. In addition, in-transit safeguards systems are considered. An approach to the definition of performance measures for a set of Generic Adversary Action Sequence Segments (GAASS) is illustrated. These GAASS's begin outside facility boundaries and terminate at some adversary objective which could lead to eventual safeguards risks and societal harm. Societal harm is primarily the result of an adversary who is successful in the theft of special nuclear material or in the sabotage of vital systems which results in the release of material in situ. With the facility safeguards system, GAASS's are defined in terms of authorized and unauthorized adversary access to materials and components, acquisition of material, unauthorized removal of material, and the compromise of vital components. Each GAASS defines a set of ''paths'' (ordered set of physical protection components) and each component provides one or more physical protection ''functions'' (detection, assessment, communication, delay, neutralization). Functional performance is then developed based upon component design features, the environmental factors, and the adversary attributes. An example of this decomposition is presented