@Krieghund:
In Alpha, it depends on where you’re doing the assault. If you’re leaving sea zone 100 to do it somewhere else, you’re fine. However, if you’re doing the assault in sea zone 100, you must have one of your warships end its combat move in the sea zone in order to carry out the assault. This is the only exception to ignoring subs during movement.
In the box rules, the sub would just get a shot at your transport as it goes by if none of your warships move along with it.
The Amphib Asault would be a bridge from Romania to the Caucusus and therefore the Transport would not be moving at all. It could be accompanied by fighters and SZ 100 could have a surface ship as part of the placement phase, bought at the start of the turn.
Other than that it wouldn’t be moving, so no amphib asault?