Yes, sometimes control towers or other ATC facilities are constructed to support air traffic control. If, for example an ATC tower is needed (there was none previously or it was destroyed), a mobile replacement is used.
For mission control Airborne Warning and Control Systems (AWACS) are used:
But these are quite expensive to fly. If possible, mobile surface based radars are brought in to provide a surveillance picture.
Mobile towers, radars and navigation beacon are not solely used in war situations. In natural disasters they have proven to be useful as well:
FAA sends temporary Air Traffic Control tower to Haiti