I don’t really understand what the problem is… You say that Japan has Russia surrounded… With surrounded I assume you have a big stack of units in Novo, only in turn 6 that is not really possible imho and you tell us that the allies stacked in Kar and not in Russia. If it is the case that you are still building your forces with Japan, you could try a strafe on kar. Building up until Japan is ready for the 1-2 punch is also a good alternative…
Some other things.
Never, I repeat NEVER leave your arms alone! Don’t divide your forces if not necessary.
