Deterrence depends on facts an opponent can perceive, including assets whose existence is public even when their location is concealed. Submarines supply that visible invisibility at higher levels of escalation, but their concealment makes them awkward tools for routine conventional signaling. A surface ship can instead visit a port, host officials, attract press coverage, and connect hospitality to an implicit reminder of the fleet behind it. Visiting the state at issue or one of its neighbors changes alliance assumptions without firing a weapon. The added known unknowns can make diplomacy look safer than conflict.
Chapter · 20:27-24:30
Surface ships turn deterrence into visible diplomacy
Submarines create a known but hidden threat, while surface warships can use port visits to make interest and possible reinforcement unmistakable.