This book gathers the proceedings of the Multidisciplinary International Conference of Research Applied to Defense and Security (MICRADS 2021), held at Naval Cadet School "Almirante Padilla", in Cartagena, Colombia, during August 18-20, 2021. It covers a broad range of topics in systems, communication, and defense; strategy and political-administrative vision in defense; and engineering and technologies applied to defense. Given its scope, it offers a valuable resource for practitioners, researchers, and students alike.