This contribution aims to unfold the dynamics of military roles expansion on counterterrorism in contemporary Indonesia. Having supported authoritarian rule of Suharto for more than three decades (1966–1998), the Indonesian military has been an influential actor in domestic political-security spheres and continuously maintained such position throughout the democratic period. In light of the recent terrorist threats, from Jemaah Islamiyah in 2000s to the Islamic State (IS)-inspired groups in the 2010s, the Indonesian military has been involved in numerous activities to support the police forces’ counterterrorism mission. This chapter argues that counterterrorism as one form of non-combat mission has become new avenue that the military seeks to exploit in order to expand its influences over non-defence affairs in Indonesia. In addition to that, the civilian leadership’s invitation to the military to actively support counterterrorism also holds crucial role. A puzzling state of civil-military relations during post-authoritarian Indonesia has provided fertile ground for the military to reassert its dominance upon Indonesia’s democratising polity.