In the contemporary world, electromagnetic technologies have become one of the key elements in the defense policy and national security of countries, which have created significant developments in this field. The present study aims to explain the function of these technologies as tools that affect the defense strategies of countries. The main question of the present study, which is written in a descriptive-analytical manner, is how electromagnetic technologies can affect the defense policies of countries and what challenges and opportunities they create in this regard? By examining the basic concepts, history and development of electromagnetic technologies, this study provides comprehensive and substantiated information that includes details about the various applications of such technologies in military fields such as radar, electromagnetic weapons and electronic warfare. The research findings indicate that electromagnetic technologies have led to fundamental changes in the defense strategies of countries and, while revising new defense approaches, have also strengthened the ability to manage unforeseen threats. The aforementioned technologies have also led to the emergence of new threats, especially in the field of cybersecurity, which requires policymakers to constantly review and adapt their strategies. Therefore, electromagnetic technologies, as an inseparable tool of defense policies, have created profound developments in the field of national security.