It will be argued in this paper that the “sectarianization” of post-2003 regional political conflicts is the outcome of a more profound crisis of legitimacy within the regional state system and its destabilization by a long and chequered history of foreign backed authoritarian regimes and imperial interventions. This issue will be examined through the lens of the Islamic Republic’s tried and tested policy of supporting politically receptive co-sectarians and its reliance on weak central states and civil conflict for its operation, expediting the erosion of already fragile political orders, while paradoxically underwriting the Islamic Republic’s own raison d’état. More specifically the paper will compare Iran’s political and military interventions in Iraq post-2003 and Syria following the onset of the Arab uprisings in 2011. It is hoped that a comparison between the discursive framing of the two interventions in Iranian elite political discourse and an analysis of the nature and modus operandi of the material support provided to receptive groups in these two countries will shed light on the valences and processes of “sectarianization” in the Middle East post-2003. Moreover, it will be argued that the Islamic Republic’s “sectarian ambivalence” is linked to manifold countervailing logics inscribed at both the discursive and institutional levels of the politico-ideological nizām, which comprises part of the inter-state system. This is while powerful political forces within the Islamic Republic continue to view the “Islamic Revolution”, as exceptional, and thus ultimately unconstrained by the norms of that system. This politico-theological tension in tandem with the proven “efficacy” of patronizing receptive co-sectarians in weak states, has fundamentally undermined a quest for hegemony and the construction of a historical bloc under the imprimatur of the Islamic Republic’s putatively ecumenical leadership. This is despite the longstanding efforts of the post-revolutionary Iranian state and state-sponsored organizations to appeal to ecumenical narratives, including support for the Palestinian resistance and the sponsorship of initiatives calling for “Islamic unity”. Rather than simply label the Islamic Republic “sectarian” an attempt will be made to analyse the institutional and ideological rivalries within and between Iranian state institutions which propound antagonistic conceptions of the “national interest”, “regional security” and “transnational commitments” to fellow Muslims. These floating signifiers are not essentially “Shiʿi”, but represent a systematic attempt to construct an authentically “Islamic” narrative, while concomitantly marginalizing ideological adversaries, including co-sectarians.