Treading Lightly Within the Nuclear Non-Proliferation Regime: An Examination of the Non-Proliferation Treaty in the Context of AUKUS and Nuclear-Powered Submarines

In September 2021, Australia, the United Kingdom, and the United States unveiled a landmark security partnership known as AUKUS. AUKUS will give the United States a formidable tool to deter Chinese aggression by providing Australia with nuclear-powered naval submarines (SSNs). Nonetheless, AUKUS poses significant legal risks because it raises questions about compliance with the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). This Note examines the NPT text and its application to SSNs using the interpretive framework of the Vienna Convention on the Law of Treaties (Vienna Convention).The NPT classifies nuclear material in one of two ways: "nuclear weapons or other nuclear explosive devices" or "peaceful nuclear activities." However, the treaty does not define these classification terms. Consequently, SSNs occupy a grey area within the NPT because they do not clearly fit within the ordinary meanings of a "nuclear weapon" or of a "peaceful nuclear activity."Recourse to supplementary means of interpretation under the Vienna Convention indicates that SSNs cannot be considered weapons or explosives under the NPT and that non-explosive military uses of nuclear energy, including SSNs, must be considered peaceful as that term is used in the treaty. Therefore, member states are permitted to operate or transfer SSNs in accordance with the applicable International Atomic Energy Agency safeguards requirements. Consequently, if SSNs are recognized as a peaceful activity under the NPT, then AUKUS submarines qualify for an exemption from safeguards that is reserved for "non-proscribed military activities."An accurate understanding of how AUKUS fits within the NPT will generate credibility among allies, discredit opposition from adversaries, and uphold the integrity of the non-proliferation regime. To that end, this Note provides the legal analysis and historical background necessary for policymakers to mitigate risks while achieving the strategic potential of AUKUS.