How a Soviet battleship could break treaty limits

What could end the extended battleship holiday and push the treaty powers back into major construction?

A non-signatory power launching an obviously over-limit battleship, such as a Soviet design with twelve 16-inch guns, could force the treaty navies to respond.

A non-signatory naval power could provide an external shock strong enough to end the battleship holiday. A Soviet ship mounting twelve 16-inch guns would be difficult to reconcile with a claimed 35,000-ton standard displacement. Britain, the United States, and the other treaty powers would assume the published figure was false. The launch would therefore provide both the strategic threat and political justification for larger treaty-power battleships.