The attributes and characteristics of potential insider and/or external adversaries, who might attempt unauthorized removal of nuclear material or sabotage, against which a physical protection system is designed and evaluated (IAEA definition (INFCIRC/225/Rev.5).

According to the IAEA: "A fundamental principle of physical protection is that it should be based on the State's current evaluation of the threat. This evaluation is formalized through a Threat Assessment process. A DBT is derived from this threat assessment. To define the DBT, the set of threat described in the State's Threat Assessment are refined to take account of other issues (for example technical, economic, and political issues) and the particular requirements of planning for system design. To make the transformation from Threat Assessment to DBT, rigorous analysis and decision-making are essential."

For more information on Design Basis Threat (DBT), see the IAEA website.