even if it's a limited-use weapon, it's one of those in the 'gonna look awfully silly that we didn't have it' if some pint-sized power decides to dance with the big boys
... and that's really the nut of the global warfare problem for the next few centuries... distributed bellicosity.
Freelance and even commercial (narcoterroristas, anyone?) trouble-makers will be able to make and deliver their own private-label WMD with little warning and a minuscule countermeasures target profile. At least some of these will be able to leave substantial flat, brown, glowing or dead spots in the centres of major cities, making urban life in general less attractive than it was in the good old (medieval) days when mountaintop redoubts and massive stone walls were useful defences.
Countering this kind of Goldfinger stuff ain't easy.
Probably the US should get entirely out of the military business & concentrate on search engines & making oil from prairie grass. Let the folks in Europe and Africa and South America and Southwest Asia do their own thing without any meddling whatsoever from the amis. That would be good, eh Airship?