第二次ロンドン海軍軍縮会議
The Washington Treaty limits were extended and modified by the London Naval Treaty of 1930 and the Second London Naval Treaty of 1936. During the 1930s, however, the effectiveness of these agreements broke down, as some signatory powers (in particular Japan) withdrew from the treaty arrangements and others only paid lip service to them. By 1938, Britain and the USA had both invoked an 'escalator clause' in the Second London Treaty which allowed battleships of up to 45,000 tons displacement, and the Treaty was effectively defunct.