All personnel of the Government of the United States Virgin Islands, including personnel of authorities, independent boards, agencies, and other instrumentalities of the Government of the United States Virgin Islands, who are members of an active reserve unit of any branch of the armed services of the United States, shall in addition to any accrued leave be entitled to administrative leave with pay for time spent in mandatory attendance at annual reserve summer training encampment, and at regular drills and training sessions conducted throughout the year.