SOSUS and SURTASS build an ocean surveillance network

The Integrated Undersea Surveillance System joins fixed SOSUS hydrophones with SURTASS surveillance ships towing very large arrays. Positioned away from the immediate battle area, those ships can collect theater-scale acoustic data while reducing their exposure. Reports from sonobuoys, combatant towed arrays, submarines, and satellites enrich the same picture, giving NATO and the US Navy broad awareness without making the system infallible. Global coverage would require far more surveillance ships distributed across the Atlantic, Pacific, and Indian Ocean instead of a few assets concentrated in priority theaters.