Threat assessment and vulnerability of infrastructure have always been the main concerns of those responsible for security in a country. This issue is so important that in many cases can lead to a significant reduction of vulnerabilities or to minimize the consequences of a threat. In fact, describe and assess threats and risks in the national infrastructure, is a framework for analyzing and managing the risks associated with the possible attacks against critical infrastructure. Thus, this study seeks an appropriate model for the assessment of threat, vulnerability and risk analysis in accordance with the threatening situation in the country. The aim of this paper is to provide a framework for the precise assessment of threat, vulnerability and risk of critical infrastructures of the country with passive defense considerations in accordance with the strategies of the foreign enemies. In this perception, the critical national infrastructures are considered as the first targets of possible attacks. The approach of this paper is an investigative approach to achieve the passive defense criteria and trying to find tools and resources to transform concepts and recommendations qualitative and quantitative criteria. If the passive defense is defined as unarmed actions, contrivance and prepararion against of the external threats should be analyzed and evaluated.