Ft Huachuca is hardly a hard target. It’s an intel base and is spread all over the desert floor. It would take 5 minutes and a pair of wire cutters to get onto this base.
When I was in the US Army I was amazed at how unprotected are the US Army bases in CONUS. No one carries weapons (other than a few MP’s) except during field exercises and even then no one has any ammo. Access to any base can be had by anyone willing to take a walk through the woods.
The first terrorist attack on a stateside US Army base would result in many casualties for the USA. If the terrorists were smart enough to hit and run, their casualities would be very light. They could kill scores of US soldiers and leave before arms rooms were opened and ammo dispersed.
Hopefully, this close call has already resulted in tighter security.