INTRODUCTION Southeast Asia is home to some of the most important sea lines of communication (MLS), which are not only important sea routes for merchant ships, but also for the warships of the superpowers. Although no accidents involving nuclear submarines have yet been recorded in this region, the fact remains that the number of such vessels passing through the Southeast Asia maritime link is predicted to increase in the coming years. MATERIALS AND METHODS. This study is the result of an analysis of international treaties applicable to the navigation of nuclear submarines. In preparing this work, the following materials were used: 1) the 1982 UN Convention on the Law of the Sea; 2) AUCUS pact (Australia, United Kingdom, USA). The methodological basis of the study is traditional methods: general scientific methods (in this case, based on the general principles of law) and special methods. RESULTS OF THE RESEARCH. Apart from China, Australia is another country in the region that is predicted to have nuclear submarines by 2040 thanks to AUKUS. These events aroused the concern of the leaders of the countries of Southeast Asia, especially Malaysia and Indonesia - the states responsible for ensuring security in the Straits of Malacca and Singapore, as well as the Indonesian archipelagic sea corridors. Thousands of ships cross these sea lanes every year, including nuclear submarines belonging to states that already own them. DISCUSSION AND CONCLUSIONS. In conclusion, the article emphasizes that international law must strike a fair balance between the rights of navigation and the protection of the marine environment, especially on maritime lines of communication subject to freedom of navigation in relation to nuclear submarines.