Spanish super-battleships strain the treaty system

How would two fast Spanish battleships with twelve 15-inch guns affect the interwar naval treaties?

Spain could not be ignored, but including it would pull South American powers, Russia, and Turkey into negotiations and make a stable tonnage agreement much harder to achieve.

Two fast ships carrying twelve 15-inch guns apiece would be too powerful for treaty planners to ignore. Their construction could revive the South American naval competition by pushing Chile, Argentina, and Brazil toward new purchases. Bringing those states and Spain into the negotiations would raise the question of including Russia and Turkey as well. Russian demands for parity with Japan would then press Japanese, British, and American allowances upward. The likely outcomes are a much less restrictive agreement or a treaty system that breaks down during negotiation.