Re: In today's news...
I remember many times having to be able to deploy within 24 hours of receiving a phone call many times, sometimes sooner, sometimes as long as three days. I was never able to travel more than 3 hours away from the military base I was stationed at at any time without direct permission. A military vanguard can be deployed rather quickly. Like, within hours. Local Police even quicker, and if the States is anything like Canada, than any city must have a Tactical Police Unit that will be able to deploy just behind street level officers.
Now we've just seen a street level officer take out one guy without being eaten, so if they see this going on whole scale, they can react accordingly as well. And Tactical Police Units are rather well armed (assault rifles, SMGs, snipers, etc.) and very well trained, those guys, whether SWAT, TRU, ERT or some other name, they know the business of putting bullets down range and saving people.
And frankly, pretty much every pair of boots on the ground knows what a zombie is. They'll know how to react even if generals don't, and I know during my deployment, my company commander made most decisions on platoon movements and such. Generals only put us in a district. Soldiers know how to react to a given situation, and officers on the ground can move their platoon and react to a given situation, and Majors with their companies, and Lt Col's with their brigades... really the people at the tippy top don't decide how the man on the ground will actually put a bullet into someone's eye socket. Real military operations do not work like RTS games. Basically even if the people at the top most levels of command can not grasp that a zombie apocalypse is upon them, the guy's on the ground will still be able to fight back due to the one ROE that goes into any deployment: "Self Defense". Even the UN troops would be able to shoot a man trying to eat them.
Also military armouries still can't just be strolled into. At least not the ones I know of. The only one that would actually be easy to break into is empty most of the time (I've worked in it a few times being the Ammunition NCO for a few ranges), they others have rather thick doors, walls, and alarms that would just bring hordes of zombies down upon you. Or other looters... or remaining military going to rearm.