Any person who is a duly qualified member of any of the reserve forces of the United States who, in order to perform any military service he or she may be called upon to perform by proper authority, leaves a position, other than a temporary position, in the employ of an employer, who shall give evidence of the satisfactory completion of that training, and who is still qualified to perform the duties of that position, shall be entitled to be restored to his or her previous or a similar position in the same status, pay, and seniority, and this period of absence for military training shall be construed as an absence with leave and, within the discretion of the employer, the leave may be with or without pay.