Originally Posted by T. A. Gardner

This is a reasonable position, that the Japanese would meet alert opposition in the PI. After all, the US had nearly 9 hours warning that they were now at war.

As to the effectivenenss of the USAAF in the PI, this is more debatable. The US had about 100 or so fighter aircraft in the PI total. Of these about half were either early model P-40 or older obsolesent P-36 or P-35s. These aircraft would have proved very marginal against the Japanese and would have been quickly lost in aerial combat. The more modern P-40Es would likely have put up a decent fight before being reduced to ineffective numbers as well.
The problem for the US is that they cannot readily reinforce or replace their losses while the Japanese could. Additionally, the US also lacked the means to readily repair their airfields after bomb damage again reducing their effectiveness.
I really doubt that given the pathetic level of US leadership at high levels in the PI....Sutherland MacAuthur's CoS and Brereton his air commander in particular.... the USAAF would have made a stellar performance in any case. These same two proved incapable of using air power in New Guinea when it was available following the loss of the Philippines. I would use that as a baseline to likely events in the PI as well.
So, other than causing the Japanese some additional aircraft losses the USAAF still would not have made a significant contribution to the defense of the Philippines in any case.