The Americans also abandoned the "let the Philippines go" at MacArthur's urging and moved a lot of war material there as a first line of defense, and thought sure the attack would come there - or in Malaya, but NEVER on stripped-down Hawaii. They also thought, along with some Japanese, that Japan would never be stupid enough to attack America.
However, their military had brainwashed themselves into thinking they could demoralize us with the Pearl Harbor attack and that by time we recovered, they have fortified all their forward bases to the point we wouldn't attack and instead sue for peace. The error in timing their declaration of war did nothing but piss us off. One wonders how united this country would have been if the attack had not turned out to be a "sneak attack".
Roosevelt must have dropped to his knees and thanked God when Hitler made the idiotic/suicidal declaration of war on the U.S. I think that after Pearl harbor, we would have been so pissed at the Japs that if Hitler had held off, we would have figured he was the Europeans' problem and gone full-bore after Japan.
I understand that he thought that by jumping in, the Japs would attack Russia and take the heat off him on that front, little realizing their interest lay in the southern oil fields of the Dutch East Indies.
Great scenarios for an alternate universe.
MacArthur's overall strategy was feasible assuming the Philippines could be resupplied. Even if every American fighter in the Philippines had been protected from the initial attacks, the success of the attack at Pearl doomed the Philippines.
The Imperial Japanese Army aircraft sank USS Panay (PR-5), a US Navy Gunboat operating under treaty rights in China, in 1937 and a Kreigsmarine U-Boat (U-552) had sunk USS Ruben James (DD-245) just over a month prior to Pearl Harbor. If those incidents didn’t cause a war, a dinky yacht in the South China Sea won’t.
The yacht was a spy ship, and too little too late in December 1941.