A friend (UK) and I (Germany) are having a heated dispute.  Here is my question:

I have a destroyer in Seazone 14. He wants to attack that seazone with only air units (no navy) during the combat phase of his turn and then move naval units from his planes’ starting point (Seazone 15) into Seazone 13, moving through what was my destroyer’s territory at the beginning of the UK’s turn.

I think that even if he wins in the air battle, he cannot move through Seazone 14 (hostile at the beginning of his turn).  He thinks that he can move the naval units through if he wins because during the non-combat phase of his turn, there are no naval units occupying that seazone (hostile at the beginning of the turn, but not hostile during the non-combat phase). Game is on hold until this is resolved.

For reference, here is our board setup atm:
Seazone 13 - Not occupied
Seazone 14 - German destroyer
Seazone 15 - UK carrier (2 planes), cruiser; transport

Input from the community appreciated.