Answers to Japan's Tosa and Amagi programmes

How would Britain and the United States counter the Tosa and Amagi classes?

The American answer centered on the Lexington battlecruisers and 1920 South Dakota battleships, with British plans developing in parallel.

Japan's Tosa battleships and Amagi battlecruisers did not emerge in isolation. The United States answered with the Lexington and 1920 South Dakota classes, while Britain also had follow-on concepts. Each navy was planning against the programmes it expected rivals to complete. These unbuilt classes belonged to a connected arms race rather than separate design curiosities.