Amphibious Assault question

[Pelanderfunk]

Situation: Italy holds Gibralter with ground forces and a couple fighters – they have no navy. The US has a navy in the adjacent sea zone following a botched amphibious assault.

Question: If UK attempts an amphibious assault through the sea zone with the US navy, and Italy scrambles the fighters to force a sea battle, does the US navy participate in the pre-assault sea battle, or is it just the Italian fighters vs the UK navy?

[Gargantua]

Just Italy vs UK.