@ghr2:
closer to 25-30 ipc worth of units actually that wont be doing anything else otherwise
That is not enough to best 18 Infantry, 1 AA Gun, 2 Fighters, 1 Tactical Bomber. The Russians will roll over any Japanese incursion you send with less than 50 IPC worth of units. Hell, with the 2 armor Japan gives me, I’ll theoretically have 18 Infantry, 2 Fighters, 1 Tactical Bomber and 2 Armor (and the Strategic Bomber I generally buy anyway, because I want the utility).
Generally, when Japan invades and I retreat before them, they have over 14, 15 units including some air units and an AA Gun. All those units are now unable to attack China or defend against England, Australia and America.