Hell, a runway capable of handling a C5 and/or a few C17s *once* wouldn't be unreasonable compared to the other expenses involved in these things. It's only when you want to pound it with stuff like that repeatedly and still have the ambassador's Gulfstream get a smooth ride that it becomes a civil engineering mess.
State Dept in DC would never allow it. And never allow for an easily defensible location out of town. They're under the opinion that an occupied embassy, a dead ambassador or a handful of lower echelon employees without political connections are trivially outweighed by not having to deal with a host nation whining that we don't trust them. Dead service or security personnel don't count whatsoever, unless embarrassing news reports can't be blamed on someone else.
Diplomatic circles are a very weird kabuki theater. In my opinion, they cost us far more than they've saved our bacon. They're quite happy to throw US domestic industry under the bus, or on the flip side, throw the citizenry under the bus for a specific company. It all comes down to who bribed what bureaucrat or had the most pull at the time. "What's best for the American citizenry as a whole" is never a consideration. It's about lining up a sweet gig after retiring from State, or angling to get into a position to angle for a payday.
Another weird aspect is our foreign intelligence operates near exclusively out of State Department facilities.
The whole situation is fubar and has needed overhauling for decades.
