My bad, its just 1 sub + 1 fig you can bring to attack the Aussie fleet. (sub + cruiser + trans + 2 inf)
Seems like a good trade (average 24 defender IPC losses in excess of attacker losses)
And, if you survive with the fighter and land it on a carrier next to New Zealand, the US will have to make a choice.
Either bring some of the Pacific fleet (Hawaii) down to New Zealand to kill the fig and carrier, and thus delay atlantic fleet build up. Or just ignore the carrier+fig.