When a proper army was non-existant (or too busy to aid distant settlements), the task of defending local communities historically fell on militia – civilians with minimal military training, such as engineers, farmers and agricultural workers who took up arms in order to protect their homes and families.
In new Human colonies of the Enigma sector situation remains the same, with Militia forces being the main form of FALCON military presence. Although it is technically possible for FALCON to form a proper regular army, deep mistrust and fear between the Settlers and Wanderers prevents them from reaching the ultimate agreement on it.
Besides, creation and maintenance of such force would require expenditure of tremendous amount of resources and equipment. With secondary exploration on full throttle most resources were already diverted to foundation of new colonies and creation of complicated communication and supply lines. Thus, so far a regular FALCON army remains only a project.