Executive Order 11265, dated January 11, 1966, extended eligibility for the NDSM to service members "who served during any period after December 31, 1960, which the Secretary of Defense designates as being a period for which active military service merits special recognition." The closing date of this period of eligibility was later set at August 14, 1974 by a letter from the Assistant Secretary of Defense for Manpower and Reserve Affairs, subject: Termination of Eligibility for the National Defense Service Medal, dated June 30, 1974.