The present study explains why the UN Security Council, during the Gaza crisis (October 2023–late 2025), failed to turn “collective security” into clear, binding, and enforceable constraints, and then examines the implications of this incapacity for recalibrating the Islamic Republic of Iran’s regional policy, drawing on offensive realism.

First, building on Krasner’s theory of international regimes, the Council is analyzed as an institutional configuration of principles, norms, rules, and decision-making procedures embedded in the global distribution of power; hence, its limited efficacy is primarily structural rather than merely managerial. U.S. influence is exercised through three main channels: veto patterns, ex ante shaping of draft resolutions under the shadow of veto, and procedural control over the agenda and the resolution-drafting process. Council performance is assessed at two levels: output effectiveness and outcome effectiveness. For outcome effectiveness, the metric is the gap between Council demands and field conditions as reflected in UN reports. The findings indicate selective Council practice: resolutions on humanitarian assistance and certain phased frameworks were adopted, whereas calls for an immediate and unconditional cessation of hostilities often failed due to U.S. vetoes or bargaining structured around Washington’s preferences, entrenching a persistent gap between humanitarian norms and enforceable operational rules.

Second, the article argues that, from an offensive-realist perspective, this selective enforcement strengthens Iran’s incentives to reduce reliance on institutional constraint and to pursue a calibrated maximization of deterrent and diplomatic leverage, including networked deterrence, deniable capabilities, wedge diplomacy, and contestation of legitimacy in veto-free fora.