Corinthian Reasons why the peace should end and plan for the war:
Victims of aggression
Superior manpower and military experience
Advocate for the building up of a naval force from the funds in Olympia and Delphi.
Advocates for undercutting Athenian navy by offering rowers more
Foster revolts among Athenian allies
Building fortifications among their country
Grievances for the outbreak of war
Corinth that the Athenians were besieging her colony Potidaea
Athens had grievances against the Peloponnesians for supporting a revolt of a city which as in her alliance and joining the Potidaeans in fighting against her
Apparently this was all considered private initiative of Corinth and therefore war had not yet broken out.