Not much. If the brass so desired, they could send a Prime BEEF team in, by ship if there's no runways, to set up/clear airbase ops. Such teams include ATC teams, portable radars/LORAN, fire crews, and fuelies. C-17s are very well-designed for rough-airstrip ops, and carry a hell of a lot of cargo. These planes, four-engined jets carrying about as much as a couple C-130s, can work on dirt runways if need be. This is a mission we trained for in the early 90s. I would imagine the capability nowadays is much further advanced.