Debates about whether to retain or abolish nuclear weapons have intensified. The North Atlantic Treaty Organization (NATO) maintains its nuclear weapons are essential to the alliance’s security. NATO’s 2010 Strategic Concept reasserted in 2014 that, “As long as nuclear weapons exist, NATO will remain a nuclear alliance.” Conversely, many observers of the negotiations regarding the United Nations (UN) Non-Proliferation of Nuclear Weapons Treaty (NPT) argue the Nuclear Weapon States (NWS) in the 28-member NATO alliance are obliged to move NATO’s posture toward nuclear disarmament rather than deterrence. The resarch project analyses the arguments in favour of the alliance’s continued reliance upon nuclear weapons and the arguments against its current security policy. The research project investigates the systemic-, state- and individual-level factors that interact to produce longstanding policies as well as divisive debates about NATO’s nuclear weapons. A core objective is to explain debates concerning NATO’s nuclear weapons in the context of global negotiations at UN headquarters between 1995 and 2020 about nuclear proliferation and disarmament. Two research questions are investigated: What are the distinguishing features of the NATO security policy, specifically what are its objectives, goals, and instruments? What multilateral initiatives at the UN by coalitions of Non-Nuclear Weapon States (NNWS), non-governmental organizations (NGOs) and individuals have attempted to change longstanding nuclear policies? The research project explains the struggles over nuclear weapons and NATO’s security policy – and this short paper asks whether the levels-of-analysis approach is still useful for explaining NATO’s security policy.