ORIGINAL: AirGriff
Well, what the heck. Since you'll probably lose to an auto victory anyway, then mount up a respectable assault force with tons and tons of supply/fuel and go hit the Bonin Islands. Plant a bunch of bombers out there and sink everything you can coming out of Japan to supply all his new found gains. There's no reason you have to let him have ALL the fun.
Make it an all out deal. You'll have to go way around to try and avoid his naval search patrols, but at this point you've got nothing to lose. Bring lots of engineers to build up the bases, lots of aviation support, AA, a division or two per base...the whole works (you'll need everything that floats to move this stuff). Whether it works or not, he'll come scurrying back with everything he's got. Maybe it'll shake something loose for you. It would be impossible IRL, but your game departed any sense of reality a long time ago.
Actually I got almost the exact same reply in my AAR hehe. Guess it is about time to do something totally unexpected [:D]
Terje


