Welcome to the forum. :slightly_smiling_face:
From the rulebook, page 11:
“Movement into a hostile territory counts as a combat movement whether that space is occupied or not.”
When you build sea units in a SZ adjacent to an IC with enemy surface warships, your opponent has to choose to retreat or conduct combat their turn. Because units from both sides were in the sea zone at the beginning of the turn, who is the attacker and who is the defender?
Thanks
The player who decides to perform combat moves on his turn is the attacker.
@Panther Thanks!