This book investigates the intricate relations between the United States, Iran, and Saudi Arabia within the Persian Gulf, conceptualising their ties as a strategic triangle. It underscores the interconnectedness of their interactions, wherein changes in one bilateral tie can reverberate across the other two. Spanning from 1969 to the present day, the narrative unravels the complex tapestry of interactions between the three actors, emphasising how ideological constructs, state identities, and leadership preferences influence not only how they perceive one another but also the strategies they choose for the region. Employing a Neoclassical Realist framework, the book offers a nuanced analysis that balances regional particularities with systemic pressures. Moreover, the analysis blends insights from International Relations theory with Middle East Studies, bringing interdisciplinarity to shed light on a phenomenon that has been central to the dynamics of the multipolar Persian Gulf system for over four decades. By delving into the historical evolution of the four manifestations of this strategic triangle (1969–1979; 1979–1989; 1989–2003; and 2003–2014), the book elucidates the intricate web of power struggles, alliances, and conflicts that have influenced much of the region's geopolitical landscape. By unpacking these factors, it provides a deeper understanding of the underlying forces at play in the Persian Gulf, offering valuable insights for scholars, policymakers, and practitioners alike.