veteran ' s service ; 2 ) a VA psychiatrist or psychologist , or contract equivalent , confirms the claimed stressor is adequate to support a diagnosis of PTSD ; and 3 ) the veteran ' s symptoms are related to the claimed stressor . This recent regulatory change has eliminated the requirement for submitting credible supporting evidence of the claimed in - service stressor if it is related to the veteran ' s " fear of hostile military or terrorist activity . " For purposes of 38 C . F . R . § 3 . 304 ( f ) ( 3 ) , " fear of hostile military or terrorist activity " means that a veteran experienced , witnessed , or was confronted with an event