Antisubmarine Defense

the totality of combat actions by large and small naval units, as well as special measures taken by the command, to protect ships and important shore installations against attack by submarines.

Antisubmarine defense includes the organization of search and destroy missions by antisubmarine ships, submarines, and airplanes or helicopters and the organization of submarine observation by permanent and mobile equipment, as well as a system for warning and communications. It also encompasses direct antisubmarine protection for ships and vessels during sea crossings and at base, and the use of obstacles, such as mines, nets, and booms.