I think that all NPC classes can now be used for combat. Presumably those military NPCs will just be better as they have the skills to use weapons (once thats implemented). Plus, you can make all NPCs walk around to get XP as well. And you can equip them with a sensor pack, wear one yourself, and then share sensors with them.
You select the NPCs at your location, and choose the 'Patrol' option in the drop down menu. Then you can set waypoints for them to walk to, and they will then continuously walk between them.
THe number of squads you can do this is given in the Ground Combat rules page.