As for ignoring Japan, I usually do. But on occasion I have used a US Pacific focus/KJF, most recently in my 4th game against Kobu last year, it’s in the Games Section.
The basic key is ignoring Europe. As US you CANNOT do both, it is either Europe or Japan. I can’t stress that enough.
Here’s what I try and do:
US 1 - buy air - 2 or 3 ftrs, maybe 4 inf, make it look as if you’re going to Europe, trn with 2 inf to UK sz/or Afr, Pac ships to Pan sz like they are going to the Atlantic.
US2 - buy AC and subs for WUS sz, move back ships to WUS sz from Pan sz
US 3 - buy at least 1 sub, 1 trn - matching any Japan naval purchases, buy 2 inf for the trn.
Take back HI if you lost it, move any inf towards Ala
US 4 - consider buying AC/ftrs, otherwise go 1 or 2 subs and trn with inf.
Take the solomon islands, with as much of the fleet needed to protect all ships. Make sure Japan’s navy can’t beat yours. You should have at least 1 BB, 1 AC, with 2 ftrs, 2 subs, 2 trns. Use excess subs to block a Japanese assault on the Sol Is sz and HI.
This will be your “Southern Base”, since you can reach multiple islands from here.
US 5,6,7 and on - continue buying 1 sub, 1 trn, and inf and look for the oppurtunity to buy that second AC, as you should have 4 ftrs. Don’t forget your bomber too.
You start a pattern of sending out sacrificial trns with 2 inf to pick off islands with your air, while a new sub with 2 new inf arrive in the Solomons. Let Japan go after your lone trannies, you may shoot down some ftrs and if they use lone subs, your air can eliminate them.
Use excess subs to block Japan’s navy and protect your main fleet at the Solomons while new ships and inf get placed in WUS.
Japan can’t make a credible threat to the WUS without you being able to move your entire fleet back to protect.
Now when Japan moves it’s fleet South to start taking back some islands, leave some blocker subs and head back to WUS where you just made a tran and inf purchase (1 or 2 trns, rest inf). You should have at least 5 trns with your fleet and the ability to get more than 10 inf to Ala your next turn.
Then you go to Ala with fleet and 10 inf. Japan will have to pull back the bulk of it’s fleet to protect Japan. Now you have to bide your time, sending out blocker subs, a trn here or there should still try go to the South Pacific and pick up lone islands. But still send 1 sub, 1 trn with inf to Ala each round. Unless you think you really out class Japan’s navy.
You should have 2 AC’s, 4 ftrs, 1 BB, 6+subs, 6+trns. Now send what trns with inf you can to SFE, with whatever subs you need to defeat any Japanese blocker sub in the SFE sz. Take SFE with 10 inf (assuming you have enough ships to left protect your fleet in the Ala sz).
If you ever have the oppurtunity to eliminate Japan’s fleet - take it!
You should start a shuck-shuck type system from Ala to SFE, but maintain naval and air superiority at all cost.
If you can safely move your fleet to the SFE sz take that so you can transport 8-10 inf from Ala to SFE a turn. You should still be able to send ‘blocker’ subs to prevent Japan from heading to the WUS.
You should earn a min of 32 IPC, and you can get in the high 30’s briefly as I’ve taken the Phil Is, East Indies, Bor, NG, even Fic or Kwa. Never all at once, unless the game is basically over, but each at differnet times.
You can really slow down Japan and keep them earning low 30’s or even high 20’s. And if they are buying ships that means no inf to go against Russia. Russia can even sneak in later and take Fic/Kwa or Man at times.