Comparing the alternative opening targets

San Francisco promised maximum emotional shock but required the longest approach and probably only two carriers. Alaska was closer and vulnerable, while the Philippines could create a relief trap only if Japan deliberately left a garrison holding out. Radio broadcasts from that garrison and continuing Japanese artillery could sustain public pressure for a relief expedition. Such deliberate strategic manipulation would have been dishonourable, and the Japanese high command probably would not have chosen it. Singapore and Sydney could absorb a six-carrier blow while overloading British defences and complicating American entry into the war. Sydney lay about 4,300 nautical miles from Japan but only about 2,900 from the Marshall Islands within Japan's South Seas Mandate, making the staging problem less extreme than a Tokyo-centred map implied. Pearl Harbor remained the most balanced target once Japan chose to attack America, combining national territory, a major naval base, a workable approach, and weak defences.