Before the operation, you'll get your regiment and it will remain static - losses and veterancy aside - throughout the op. However, you'll be able to attack task forces to it, choosing them in this screen - not in the field like we saw in skirmish mode. This also where you spend your operation authority - gained for conquering zones on the map - to increase your deployment limit, amount of supplies, tactical aid points, and engineer points.
Only deployment points are permanent - the rest are very much consumable as you'll soon learn.
