Why German cruiser construction would trigger an early British answer

Would a German fleet of twelve Deutschland-type ships and twelve 20,000-ton cruisers trigger new Royal Navy heavy-cruiser construction?

Yes, but the trigger would be the German building program itself, allowing Britain to begin its response before the ships entered service.

An arms race unfolds through visible building programs. During the years required for Germany to construct twelve Deutschland-type ships and twelve larger cruisers, Britain could design, launch, and commission its answer. With treaty limits weakening, that response might include new heavy cruisers or numerous light fleet carriers rather than a mirror-image fleet.