Why three Lexington battlecruisers would unravel the treaty balance

Could the United States have traded three older battleships for three Lexington-class battlecruisers under the Washington Treaty?

Probably not without reopening the agreement, because Japan and Britain would demand comparable 16-inch-gun additions.

The swap fails because three additional American 16-inch-gun ships would alter the treaty's negotiated balance. Japan would seek an equivalent concession, while Britain would likely demand a much larger Nelson-class programme. A six-ship British run might even justify a faster design than the two historical Nelsons. One apparently tidy substitution could reopen the entire capital-ship settlement.