N.D. Cent. Code § 37-02-07
The number and grade of officers and enlisted men in the state staff corps and detachment must be as prescribed by federal law and regulations, but in case of war, invasion, insurrection, or riot, or imminent danger thereof, the governor may increase such force temporarily to meet such emergency. All appointed officers of the state staff corps and detachment must have had previous military experience and shall hold their positions until they have reached the age of sixty-four years unless retired prior to that time by reason of resignation, disability, or for cause to be determined by an efficiency board or a court-martial legally convened for that purpose, as the exigencies of the case may warrant. Vacancies among said officers must be filled by appointment from the officers of the national guard or from other classes eligible under federal law or regulation.
N.D.C.C. § 37-02-07