Stalin's personal participation would bring Soviet status and fleet distribution directly into the London negotiations. A demand for parity with Japan would force the powers either to invent another treaty tier or raise Japanese, British, and American allowances. France and Italy could not easily accept a lower category to make room. Japan would also reject reliance on a promise that Soviet Pacific and western fleets could never combine, turning the conference into a wider tonnage escalation problem.
Notable Point · 7:25-9:04
Why Soviet participation could destabilize the London Naval Treaty
Adding Stalin's Soviet Union to the 1930 treaty negotiations would disrupt the established ratios among Britain, America, Japan, France, and Italy.