This research is conducted with the aim of examining the legal challenges arising from the transfer of nuclear submarine technology under the AUKUS Pact (2021) among the United States, the United Kingdom, and Australia. The research method is descriptive-analytical, and the data have been collected through library resources and international documents. The main issue of this research is the potential incompatibility of this pact with international obligations in three areas: the law of the sea, the environment, and the non-proliferation of nuclear weapons regime. Considering Australia's declaration of readiness to participate in multinational military operations in the Strait of Hormuz, the possible use of nuclear submarines in such operations is not regarded as innocent passage under the laws of Iran and is considered contrary to Iran's security, while also endangering the protection of Iran’s marine environment in the Gulf of Oman and the Persian Gulf. The findings indicate that the AUKUS Pact is inconsistent with Articles 192 and 194 of the 1982 United Nations Convention on the Law of the Sea (UNCLOS) regarding the protection of the marine environment and the prevention of radioactive pollution. Furthermore, the use of highly enriched uranium fuel and the lack of transparency in nuclear waste management are in violation of the 1996 London Protocol and the principle of precaution. In addition, the transfer of dual-use nuclear technology to a non-nuclear-weapon state exposes oversight gaps within the International Atomic Energy Agency and undermines the objectives and foundations of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).