 On 10 July 1965 , F @-@ 4Cs of the 45th Tactical Fighter Squadron , 15th TFW , on temporary assignment in Ubon , Thailand , scored the USAF 's first victories against North Vietnamese MiG @-@ 17s using AIM @-@ 9 Sidewinder air @-@ to @-@ air missiles . On 26 April 1966 , an F @-@ 4C from the 480th Tactical Fighter Squadron scored the first aerial victory by a U.S. aircrew over a North Vietnamese MiG @-@ 21 " <unk> " . On 24 July 1965 , another Phantom from the 45th Tactical Fighter Squadron became the first American aircraft to be downed by an enemy SAM , and on 5 October 1966 an 8th Tactical Fighter Wing F @-@ 4C became the first U.S. jet lost to an air @-@ to @-@ air missile , fired by a MiG @-@ 21 . 
