Coal phase-out is an integral part of the ongoing energy transition to a decarbonized economy. Any such process involves diverse actors that compete over the nature and pace of such transition. This research uses the Advocacy Coalition Framework to analyze the conditions of policy change within an adversarial subsystem. It focuses on the coal subsystem in the Czech Republic, a post-communist coal-dependent country with comparatively large economically recoverable reserves. Using data from an organizational survey, exploratory social network analysis techniques are applied to identify advocacy coalitions and deductive block-modeling is used to test hypotheses on the subsystem's functioning. The focus is on: (1) fragmentation of decision-makers, (2) targeting of decision-makers, and (3) use of expert information. Two competing and ideologically distant coalitions were identified: the Industry Coalition and Environmental Coalition. The results further show high fragmentation among decision-makers, as indicated by their cross-coalition membership and the heterogeneity of their beliefs. The targeting of decision-makers is practiced by principal members of both coalitions, i.e. environmental non-governmental organizations and industry, but also by research organizations. Lastly, expert information exchange strongly overlaps with the identified coalitions and thus increases their cohesiveness. It is argued that such subsystem configuration limits the potential for policy change through negotiated agreement or policy learning. Policy brokers and policy venues are suggested as remedies to moderate the adversarial nature of the subsystem.