How Mikasa survived the naval treaties

How did Mikasa survive the naval treaties?

Concrete encasement, demilitarization, and Mikasa's symbolic status allowed her preservation.

Mikasa survived because she was encased in concrete, stripped of operational machinery and weapons, and treated almost as a national ship shrine. Her engines and guns were removed, while the visible turrets are replicas. The ship also survived later proposals for uses such as placing an aquarium inside her. Demilitarization met the treaties' practical purpose, while demanding the destruction of so important a national symbol would have made Japanese acceptance harder.