Why active fleet spending undermines naval treaties

Would the naval treaties be signed if the parties were willing to spend heavily on their fleets?

Probably not; even a few determined spenders could unravel the assumptions that made limitation acceptable.

Britain built toward treaty limits because it remained willing to spend on the fleet. The limitation system nevertheless assumed that other signatories, especially the United States, would not fully fund every entitlement. Sustained American matching of British force levels throughout the 1920s would have changed the strategic and fiscal bargain. London might then have concluded by 1930 that the treaty could no longer be sustained, showing how arms control depends on political restraint as much as formal tonnage ratios.