Visible naval forces can apply quieter coercion than an explicit threat. A frigate requesting a port visit communicates that its government is watching and can place forces nearby. A carrier group exercising with an ally raises the possible cost of attacking that ally while still offering the other state participation and a diplomatic exit. This is gunboat diplomacy as an unspoken condition: cooperation remains available, but military power stands behind it.
Notable Point · 2:21:19-2:23:47
Naval presence makes the threat implicit
A frigate visit or carrier exercise signals interest and capability without the escalatory language of announcing a hidden submarine off another state's coast.