Protecting trade during the ninety-day fleet delay

British planners expected Japan to enjoy an initial period without an opposing main battle fleet in the region. Existing cruisers and the Royal Australian Navy would therefore have to protect imperial shipping while Singapore and Hong Kong were held for reinforcement. Once the fleet arrived, the preferred strategy was to contain Japanese naval power and sever Japan's sea communications rather than invade the home islands. That concept made trade protection and distant blockade central to the war plan. It also relied on optimistic judgments that coastal guns and aircraft would make major landings against Singapore or Australia unlikely. The maritime aims were coherent, but flawed political and joint-service assumptions left the plan vulnerable.