The controversial Iranian nuclear dossier, the Pakistani nuclear weapons programme, and the challenge posed to nuclear security by non-state terrorist organisations, such as Al-Qaeda, acquiring nuclear weapons, all raise concerns for international peace and security. The use of Islamic legal, ethical and strategic discourses about nuclear weaponry to justify their respective leaderships’ positions is a common factor. While Iran presents shari’a law as a limiting factor, prohibiting nuclear weapons, Al-Qaeda has long justified its pursuit of a nuclear capability through the Islamic faith. Pakistan has given less attention to discussion of law, but became the first, and to date only, Muslim state to develop a nuclear arsenal, seeking to legitimise and secure funding for the development of its nuclear capability by characterising it as a Muslim endeavour. The strategic, political, and policy implications of the Islamic nuclear discourses of these three actors, including their impact on the non-proliferation regime, regional stability, and national and international security are vital issues. Islam has served as a vehicle to promote national and regime interests but can also have other implications and costs. Once an actor defines its nuclear programme or ambitions in Islamic terms, it can only reverse its position at great political cost.