Critical infrastructure is a key element of the functional security of any country. Sea ports (but also river ports) are part of the CI system of the country. The security of such sites is particularly important for the continuity of supply and transit of goods transported by vessels. Ports have always been protected from potential threats. Today, these threats have become more real, particularly as a result of the Russian Federation’s attack on Ukraine. Poland, which today has the status of a frontier state, is a target of espionage and sabotage activities. Security is a state of non-threat. This is the state to which we aspire in every area of modern life of every society, every country. Seaports, like other places, which are essential (special) for the unimpeded and secure delivery of goods. They’ve always been under special surveillance and special protection. Destruction of the port makes it impossible to transport by sea, which is obvious. Threats to port security come from different sources, but at a time of ongoing war in Ukraine, terrorist attacks come to the fore. It is also necessary to highlight the hybrid actions on the border with Belarus, which affect the state of security. Poland, as a front-line country, is particularly vulnerable to acts of terror, diversion and espionage, which is confirmed by the actions of the special services. Monitoring of seaports is part of the security strategy of the critical infrastructure of these places. The threat of CI ports is real, especially at the present time. This applies in particular to the LNG terminal in Świnoujście, which is regularly visited by ships (gas carriers) supplying raw materials of strategic importance. Violation of security rules (principles) may lead to a threat that cannot be ruled out, however, the most important and dangerous are those that come from the outside and are of an intentional nature.