An 18-inch treaty baseline would reshape cruiser limits

What would a naval treaty look like if 60,000-ton, 18-inch-gun battleships already existed?

It would likely accept 18-inch capital ships, encourage still larger Japanese designs, and push cruiser categories upward.

If 60,000-ton battleships with 18-inch guns were the starting point, a treaty would probably codify that capability rather than force it back to the historical limits. Japan would then face pressure to build something still larger, perhaps with 20-inch guns, at severe industrial cost. A higher battleship ceiling could also pull heavy-cruiser limits upward, possibly toward 20,000-ton ships with 12-inch guns. In that environment, a 14-inch capital-ship gun would sit awkwardly between cruiser and battleship categories. The ships already in service would shape which limits negotiators could plausibly impose.