What if Britain and the United States obtained Yamato's specifications in the late 1930s?
Short answerJapan would probably continue construction, while Britain could enlarge the Lion design to twelve 16-inch guns and the United States would be pushed toward a comparable response outside normal treaty assumptions.
NotesThe answer assumes that exposing the design would not persuade Japan to stop building it. Instead, reliable intelligence would force the Royal Navy and US Navy to answer the threat, with a twelve-gun Lion offered as the British path. Knowledge of Yamato also removes the political basis for pretending that existing escalator limits still define the competition.