This is covered in the rulebook:
Multinational Forces: Transports belonging to a friendly power can load and offload your land units. This is a three-step process:
1. You load your land units aboard the friendly transport on your turn.
2. The transport’s controller moves it (or not) on that player’s turn.
3. You offload your land units on your next turn.
Unloading in an enemy territory occurs in your scenario in US’ combat move phase, followed by the battle.
Unloading in a friendly territory occurs in US’ NCM phase.
Thanks, sorry I missed that.