The scientific article studied and explained the content of the legal and regulatory grounds for the use of weapons by ships, boats and support vessels of the State Border Guard Service of Ukraine. This problem is understudied.
 With the help of general and special methods of scientific knowledge, the authors have researched the laws of Ukraine, current subordinate legal acts and scientific sources that regulate the grounds for the use of weapons of ships, boats and support vessels of the State Border Guard Service of Ukraine.
 The work clarified the content and features of the legal support for the use of weapons of ships, boats and vessels.
 It has been established that the measures of the legal regime of martial law or a state of emergency, in the implementation of which the state border protection authorities take part, determine the possibility, necessity and grounds for the use of weapons by ships, boats and support vessels of the State Border Guard Service of Ukraine.
 Most of the reasons for the use of the weapons of ships and boats can be aimed at ensuring the measures of the legal regime of war, and in some cases, the state of emergency. In such conditions, the subordination of ships, boats and support vessels of the State Border Service of Ukraine may change, which determines the entity that grants permission to use their weapons after a warning.
 The authors come to the conclusion that the reasons for the use of weapons by ships, boats and vessels of the State Border Guard Service of Ukraine, which are defined in the laws of Ukraine, are aimed at the forcible termination of offenses and crimes, ensuring compliance with measures of martial law and state of emergency. The blanket form of the norms regulating the grounds for the use of weapons on ships and boats makes it necessary to refer to other laws and subordinate legal acts of Ukraine and to take into account the specifics of the law enforcement, service and combat activities of the State Border Guard Service of Ukraine and the conditions of the legal regime of martial law or a state of emergency.