so in the case of someone placing in the sea zone if you choose to attack you can bring in other troops to that fight?

My scenario is America came from the west coast and is sitting in sea zone 60 with there navy and a destroyer and transport with a guy and a tank in sea zone 57 during japans turn i place a destroyer and sub in sea zone 60 during America’s turn they fought the destroyer and transport forcing there combat move can america move the destroyer and transport with the tank and guy into sea zone 60 for an amphibious.  My take on it is that you could not bring any sea units to sea zone 60 cause you were forced into combat there and if thats correct does a sea zone work like a territory in that you cant in that zone since it was hostile that turn?