Summary: The Concept of Deterrence and Defence of the Euro-Atlantic Area, developed in 2020, and the NATO Strategic Concept 2022 created a strategic framework for activities in the Baltic region. Deterrence as a means of avoiding armed conflict and the preparation of coherent and executable regional plans for collective defence are crucial. Following the accession of Sweden and Finland, the Baltic became the „internal NATO lake”, which increased opportunities for defence cooperation and strengthening the security of critical infrastructure. Russia's Baltic Fleet remains one of the most important elements of the threat to NATO countries in the region. Its military potential, including various missile systems, influences the need for joint operational planning and expansion of the Alliance's defence capabilities. Specific critical areas such as the Danish Straits, the Gulf of Finland or Gotland play a key role in defence plans and deterrence strategies. Operational planning must address both hybrid threats, as well as attacks on subsea infrastructure, and full-scale warfare. As part of its deterrence, NATO has already been monitoring the activity of the Baltic Fleet and has carried out critical infrastructure protection missions, such as Baltic Sentry. The cooperation of NATO countries in the Baltic region allows for effective repelling of threats and operational support for collective defence. Purpose and research methods: The data for analysis were obtained using the observation method, narrative literature review, doctrinal and conceptual documents, and the analysis process used methods of comparison, inference, abstraction, deduction and induction. Conclusions / recommendations: The Baltic Fleet is a key element of the Russian Federation Navy and plays a fundamental role in ensuring maritime security and state policy goals. Modern operation planning should take into account two perspectives of hybrid threats and the threat of full-scale armed conflict. Effective repelling of threats of Russian aggression from the sea is possible mainly in the international dimension – allied. Fulfilling the tasks assigned to NATO naval forces in the Baltic Sea also requires that the Danish Straits be an integral part of this area of maritime operations. The operational planning of operations in the Baltic Sea should take into account the specificities of the demarcation line between the two operational commands of the JFCBS and the JFCNF. After Finland and Sweden joined NATO, the Baltic Sea de facto became the "inner sea of the Alliance", which implies the need to build more in-depth cooperation between the countries of the region.