In addition to any other benefits provided in this chapter, any state employee or any employee of a public educational entity in this state who is called into active service in any of the Armed Forces of the United States during the war on terrorism which commenced in September 2001, shall receive from his or her employer department or agency compensation in an amount which is equal to the difference between the lower active duty military pay and the higher public salary which he or she would have continued to receive if not called to active service. The amount of compensation required to be paid to an employee called into active service under this section shall be paid for the duration of the active military service, the length of which shall be determined by the Adjutant General of the Alabama National Guard, from the date of activation and shall be paid from funds appropriated to the employer. The provisions of this section shall be construed to provide for such payments retroactive to September 11, 2001, if applicable.