4. If your planes have any movement points left, they must try to land elsewhere. If the planes have used their full movements and their carriers have been damaged, the planes are destroyed. Ouch!
That’s in the case USA attacks.
If USA was on the defensive side (Japan attacks USA fleet in sz6) the planes are allowed 1 step to find a safe landing space, not 4. That can be an Allied-controlled territory 1 step away or an undamaged carrier with room to spare 1 step away. In this particular case : Korea or Japan (if Allies control it) or a carrier in sz5/7/16/17/18/19.