Why did Sparta initiate the series of conflicts known as the peloponnesian war

Probably one of the better reasons for them to initiate these wars was that it enabled them to destabilize the region and especially the power of their main rival in Greece in terms of military and economics. At the time this rival was considered to be Athens. The end of the Peloponnessian wars ended with Sparta coming out as the reigning power in those parts of the world and Athens being strongly decimated.