 Prior to the development of the AH @-@ 56 , all armed helicopters had been modifications to existing aircraft designed for unarmed uses . In 1962 , then U.S. Secretary of Defense Robert McNamara convened the Howze Board to review Army aviation requirements . The board recommended an airmobile division supported by 90 armed helicopters . The recommendation of the Howze Board came at the same time the Army was preparing to deploy its first armed escort helicopters to Vietnam ; 15 UH @-@ 1A Iroquois were modified with systems for mounting machine guns , grenade launchers , and rocket pods . 
