The book explores the legality of unilateral humanitarian interventions in the post-Cold War world under the UN Charter, from an international law per-spective. Despite the UN Charter prohibition of threat or use of force in Article 2(4), subject to two narrow exceptions based on right to self-defence of states and collective measures taken under the Chapter VII of the Charter, some states intervene militarily against other states, citing humanitarian reasons, without Security Council authorisation. This practice intensified in the post–Cold War period, prompting scholars and states to propose a ‘third exception’ to justify intervention under humanitarian grounds in cases where the Security Council fails to act decisively. This exception, if recognised, would supplement existing exceptions in Article 51 and Chapter VII of the UN Charter. The main query of this book is ‘why post–Cold War humanitarian interventions, despite violating Article 2(4), are considered legal under international law’ with the aim to assess the legality of pretextual humanitarian interventions under the UN Charter from an international law perspective. The book employs a doctrinal approach in international law, utilising qualitative methods and primarily secondary data and argues that unilateral interventions, not authorised by the Security Council, are unlawful. The work finds that to address this conundrum, the ‘Responsibility to Protect’ (R2P) initiative, introduced in 2001, later recognised by the UN World Summit in 2005, purports to address atrocity situations by sharing responsibility between sovereign authorities and the international community based on a ‘Three Pillars’ structure. To circumvent the challenges posed by ‘humanitarian’ interventions, the recommendations of the book include urging the Security Council to act promptly and decisively, refraining from undue use of veto power. Additionally, it advocates for the shared responsibility of sovereign states and the international community, based on the three pillars of R2P, and emphasises leveraging UN bodies to prevent atrocities. Exploring modalities for effective R2P implementation, including utilising General Assembly recommendations, and invoking the ‘Uniting for Peace Resolution’ when the Security Council is paralysed, are pivotal aspects. It is paramount to utilise UN bodies to prevent and end atrocities while sovereign states are urged to resolve domestic turmoil timely and objectively with the necessary will. The book emphasises the illegality of unilateral use of force under the banner of humanitarian imperatives and cautions against its abuse in a multipolar world. In summary, the study establishes that unilateral use of force under humanitarian pretext, termed ‘humanitarian interventions,’ is unlawful under the UN Charter and proposes measures to address mass atrocities within the UN Charter framework suggesting alternative means to address human protection needs, underscoring the importance of upholding international legal norms and preventing the abuse of unilateral force in a polarised world divided by diverging ideologies.