Armageddon is one of my favorites. Great cast and great lines. "I wanna name [the asteroid I discovered] Dottie after my wife. She's a vicious life-sucking bitch from which there is no escape." 
I also like The Core for some reason.
I'm happily married almost 43 years now, but I laughed at that line in Armageddon!
My mother had 4 husbands.
Back to subject National guard.
The military is designed to be Self sufficient and effective in a place where there is no regular
support systems as we are used to.
Cops have SWAT teams, but they don't have a very long logistics support line.
Guard and military can go anywhere in the world and execute the mission.
Until activated the Guard is under the command of the state Governor,
which makes them legal on American soil. It also limits what they can do.
SWAT kills with impunity, Guard has the Kent state history and they won't
repeat that.