Blockade, oil, and Anglo-American pressure

Britain's likely response is patient economic warfare rather than a rushed decisive battle. If Hong Kong falls, the British can wait until conditions favor a counterstroke while keeping their own trade routes largely open and attacking Japan's dependence on overseas resources. American neutrality or intervention still matters because Japanese oil and much of Japan's trade are tied to the United States. British cruiser deployments and distant blockade positions around Southeast Asia, Canada, South America, and the wider Pacific approaches can therefore isolate Japan without sending the battle fleet straight to the home islands.