The former soldier said the Iraq Historic Allegations Team needed to "stop their witch-hunt of British soldiers, particularly ones who may well have saved lives by stopping attacks on British bases."
"Here we have a crack shot, who neutralised a threat from nearly a mile away - well over the range where a shout could have been heard from - and we have civil servants and ambulance chasing lawyers trying to nail him for criminal charges.
"He should have been mentioned in dispatches," he added.
"What do IHAT expect of soldiers in that situation? To yell at an armed man and expect him to turn around and drop his weapon and never return?
"This situation is one of the classic examples in International Law where we can clearly say the action taken was pre-emptive self defence.
"No wonder the Ministry of Defence and HQ LAND have given up on the Army 2020 strategy: who would want to join the Armed Forces these days when if you do your job properly you might get thrown in prison or we might end up with Jeremy Corbyn as Prime Minister so you'll probably be sacked anyway."