Excellent comments. I would like to add some more food for thought.

Pearl was attacked to protect the flank of the Japanese Southern Operation. If the fleet had not been there I doubt that any attempt to attack it would have been made. The Japanese cabinet tried to cancel the attack at Pearl Harbor and was only approved because Yamamoto threatened his retirement if the plan was not approved. If an invasion was attempted it would have required around 50,000 men. Men sorely needed in the South. Hawaii unlike Wake, Midway or the Philippines had an extensive bunker system, similar to Tarawa and Iwo Jima, an assault on the islands of Hawaii would have weakened the flank of the Southern Operation not protected it.

Now if the Fleet had not been there, would Japan have tried to attack the Philippines? I and 50/50 on this one, part of me says they would still need to, but the other part recalls the adage “let a sleeping dog lay.” Most of the men in the Imperial Japanese Army/Navy new that Japan would loose a war against the US. Would the US have declared war because of further Japanese aggression. Remember that it took Pearl Harbor, to override the large isolationist sentiment.

The Panama Canal would have been a far stretch and as pointed out a tough egg to crack. I personally think that had the Japanese wanted to eliminate this passage way at the out set that it would provide a brilliant first blow. Imagine this four or five cargo ships loaded up with explosives, sail in together and would fill up at least two locks if not more, once a group gets to the center lock, all the ships ram the nearest gate and blow themselves up. Kamikaze attacks. Now this would have destroyed the affected lock if no the entire canal all together with the resulting flood. What do you think?

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The Muslim Brotherhood “must understand that their work in America is a kind of grand Jihad in eliminating and destroying the Western civilization from within and ‘sabotaging’ its miserable house by their hands..." — Mohamed Akram. http://jihadwatch.org/