Rocket in Midway; Rocket in Hawaii; Rocket in Alaska = 10 IPC to W. USA
Rocket in Yakut; Rocket in China = 7 IPC to Russia
Rocket in Sinkiang or India = 4 IPC damage to Caucasus
Assumed = 3.5 IPC damage on average per rocket. Since you cannot have 0.5 IPC lost, I assumed the extra 0.5 wasted in W. USA would be applied to Caucasus just to keep the numbers even.
21 IPC in rocket damage to Russia/America isn’t too bad. Couple that with 2-3 battleship bombardments on W. USA per round for another 6-9 IPC in lost infantry (costs you an additional 3 IPC for an infantry of your own, but so what?) and you can easily be doing 19 IPC in damage to America per round with Japan.