[fso301]

They also lacked air units appropriate for naval interdiction. The three squadrons of A-24 divebombers that were on the way (the light bomber group ground crew was in the Philippines, but without planes; they were all captured) would have been ideal, but they would also have required time to train, and they would require replacements to stay in the fight. Attrition would quickly exterminate any fixed body of combat planes.

The A-24's would have been helpful but like most everything else, MacArthur wasn't expecting to have Luzon near target strength until circa 3/42.

A significant force that was available on 12/8/41 and might have profoundly impacted the course of events had it been employed were submarines. Something like 30 subs were based in Manila but the navy in it's infinite wisdom responded to repeated war alerts by re-checking mooring and anchor lines.

[buwaya]

The Asiatic Fleet was depending on the submarines as its main striking force. This was probably unrealistic, but is everything had gone as well as possible they may have made it expensive for the IJN. They failed badly, mainly due to poor training and the scandalous state of the torpedoes.
Both problems were the fruit of a dysfunctional bureaucracy in that branch.