This book provides a concise account of 159-page long and extremely complicated Iran nuclear deal (formally known as the "Joint Comprehensive Plan of Action" or JCPOA), including the legal analysis of its main content, the legal meaning of President Trump's withdrawal from it and its link to a Security Council resolution, which assures its legal and political survival. Despite such assurance, however, the JCPOA is destined to cease to exist if nothing is done before October 2025. The author has researched on international law of nuclear non-proliferation for more than 40 years. He is currently a member of the UN International Law Commission (ILC) and an associate member of the Institut de droit international (IDI).