How the 1936 naval treaty's safeguard clauses worked

The treaty restricted transfers of warships, while leaving auxiliary vessels outside that rule and constraining sales that could strengthen South American or Dominion fleets. South Africa and the Irish Free State stayed outside the agreement, which limited its reach. The treaty allowed replacement of accidentally lost vessels and permitted obligations to be suspended when a signatory entered a war. A further safeguard let a state depart from the limits when construction by a non-party threatened its national security. Its escalator mechanism meant that one state's departure or concealed breach could loosen limits for all. The China Station consequently gained an intelligence task: watch Japanese shipbuilding closely enough to know whether the treaty system was unraveling. Ernle Chatfield and government ministers nevertheless presented the 14-inch gun as the new battleship standard even though 15- or 16-inch choices remained possible. The clauses show why arms control depended on accurate monitoring as well as written limits.