Spatial planning, which involves regulating the relationship between humans, space, and human activities within space, represents an interdisciplinary field encompassing military, economic, sociological, and geographical dimensions. Ensuring lasting national security and achieving comprehensive territorial defense require a strategic model that integrates these dimensions. Territorial defense planning, therefore, depends on recognizing both past and potential future threats to a nation’s geographic domain. This study employs a mixed-method approach, combining quantitative and qualitative data using a descriptive–analytical methodology. The scope of the research covers the territorial space of the Islamic Republic of Iran and lies at the intersection of defense studies and military geography. Data collection was conducted through both library-based and field research, including document analysis, expert consultations, and questionnaire surveys. The statistical population consisted of all relevant documents and subject-matter experts. Due to the specialized nature of the topic and the limited number of qualified experts, the final sample size was 70 participants equal to the total number of available experts thus employing a census sampling method. The findings indicate that geostrategic factors play a decisive role in Iran’s spatial defense planning. Specifically, six key geostrategic components were identified and evaluated as critical determinants influencing the effectiveness of territorial defense strategies against military threats.