I have successfully killed the Japanese fleet multiple times but it takes a full four turns of purchases to get it done - but it is worth it.
In order for this to work the UK must be able to put a threathening fleet together in the Atlantic to be able to help Russia deal with Germany and Italy. Make sure the UK is on the same page.
What I’m about to describe is way easier to do in the 1942 setup and even takes less commitment from America.
I will also assume that the game is being played with NO’s.
Let’s assume the US battleship has been killed and if you want, assume the destroyer and transport in SZ56 are also killed - if not, bonus.
US T1 purchase 1 carrier, 1 transport and 3 subs (if you still have the SZ56 transport then buy another sub).
After the first US turn SZ56 should have 2 carriers, 4 fighters, 3 subs, 1 destroyer and 1 transport OR if you’re lucky, a second destroyer and fourth sub.
US T2 purchase 1 battleship, 4 subs and one tech. roll.
US T2 non-combat everything from SZ56 to Alaska and also land at least two of your bombers in Alaska as well.
US T2 place all purchased units in SZ56.
Now Japan is more then likely capable of attacking your boats in Alaska; however, you have a counter attack of 1 battleship, 4 subs and 2 bombers. Even if Japan brought everything over there to deal with you and built more boats the US counter will destroy what’s left.
In my experience Japan does not attack because they want to establish themselves in Asia. Japan will build more boats - fine.
US T3 purchase isn’t set in stone but it should be something like 1 bomber, 1 carrier, 1 fighter and 2 subs.
US T3 non-combat everything from SZ56 to Alaska and build everything in SZ56.
Once again Japan could attack but again your counter attack will finish the job.
If Japan doesn’t attack then no matter what they build the US must attack turn 4. Japan will likely put down one or two more hits in naval units so the attack might seem foolish - it is not. It will work. Even if you don’t kill it all, Japan will likely survive only fighters because again the US has set up a counter attack.
Before you doubt me you must try it. It works, not just once either. This has become my US strategy in both setups. Japan is way too powerful when left alone and buying doing this an India IC becomes possible, China will be able to put a few more men down to stall Japan.
The goal of this strategy is not to invade Japan, that’s never going to happen. All you want to do is delay, delay, delay. Without Japan breathing down Russia’s neck both the Soviets and British can handle Germany. Once you’ve crippled the Japs then you can slowly help in the Atlantic, plus you should still have bombers to fly back over to London.
I will repeat, don’t knock it until you try it AND it has to be full out. You can’t be putting some of your IPC’s in the Atlantic, if you take your foot off the gas you will fail. It must also start turn 1, no later.
As for US T4 purchases, another bomber, fighter and more subs. Japan will not be able to keep up, and if they are then that’s all they’re doing and that is exactly the point.