This article examines the relations between Saudi Arabia and Israel within the framework of the concept of a tacit security regime. Methodologically, the study employs trend analysis as its research method, relying on qualitative research, and utilizes documentary and library-based data collection (including official statements, declassified documents, memoirs, and secondary sources) to gather empirical evidence. Through this approach, the research explores the historical developments, behavioral patterns, and driving factors that have shaped the interactions between these two actors. The findings indicate that a shared perception of threat—particularly from Iran, resistance movements, and the rise of Sunni political Islam in the region—has gradually facilitated a cautious rapprochement between Saudi Arabia and Israel. This convergence has been manifested in intelligence cooperation, covert diplomatic coordination, shared stances on regional issues such as the Iranian nuclear agreement (JCPOA), as well as secret economic and technological collaborations. However, internal constraints (such as public opinion sensitivities in Saudi Arabia and the rise of far-right groups within Israel), external limitations (notably the Palestinian issue), as well as political frictions and mutual distrust, have hindered the full normalization of relations. The article argues that, within a tacit security regime—contrary to liberal functionalist perspectives—convergence begins with security-oriented concerns and subsequently extends to other issue areas. Accordingly, the relations between these two actors have developed not through formal treaties but on the basis of mutual interests and geopolitical necessities, and due to existing constraints, have not yet evolved into a formalized arrangement. By emphasizing the regional dynamics of the Middle East, this study contributes to a more nuanced understanding of unconventional cooperation among seemingly adversarial actors.