Paper warships as treaty bargaining tools

Is it underhanded to use an advanced paper design to gain leverage in a naval treaty?

It is pragmatic realpolitik: the proposed ship changes the bargaining position even if the final treaty prevents it from being built.

The question describes an advanced paper design used to pressure rivals into disposing of existing capital ships before its sponsor accepts modified replacements. The answer calls that approach pragmatic rather than underhanded. A design need not enter service to influence negotiations if it changes what other states fear may soon be built. The threatened programme becomes diplomatic leverage that can be exchanged for treaty concessions or retained tonnage. The exchange shows naval procurement operating as realpolitik, with plans and slips affecting the settlement alongside ships already afloat.