iarjhssIARJHSSIARJHSS2708-6267https://doi.org/10.47310/iarjhss.2021.v02i02.016Irregular Warfare and Challenges of Indonesian National Security: An Overview of Threats from Insurgencies and Terrorists GroupsPennyRadjendraPudjoWidodoResmantoWidodoPutroIndonesia Defense University, IndonesiaIrregular warfare or non-conventional warfare is not a new type of war phenomenon. This type of war has occurred and been practiced since three centuries ago. However, at this time, irregular warfare has been increasingly attracting attention of observers and practitioners of military, defense and security because it is rife in various parts of the world. This paper discusses two types of irregular warfare, namely armed rebellion and terrorism which are suspected to be challenges and threats to Indonesia's national defense in the present and future. The author uses a qualitative method with a positivist epistemological approach based on the definition of irregular warfare from the US Department of Defense which includes armed rebellion, terrorism, and crime networks. However, due to technical considerations, the discussion is limited to the first two types of irregular warfare, especially regarding the roots, impacts, and options of approaches as the potential solution.