Why a modern Washington naval treaty needs many parties

How could the United States and China create a Washington-style naval treaty for the 2030s?

They would need a multilateral agreement covering allied and proxy fleets, not merely limits on the two principal navies.

A modern Washington-style treaty could not be negotiated as a simple bargain between Washington and Beijing. Both sides would suspect that the other's allies or proxies might add naval power outside the limits. A workable regime would therefore have to define which states belonged to each security network and bring many of them into the arrangement. Arms control must account for coalition force structure as well as the inventories of the two largest competitors.