The Army took no measures to prepare British soldiers from attacks by rogue Afghan soldiers, an inquest has heard.
Lieutenant Neal Turkington (26), from Portadown, an officer with the 1st Battalion The Royal Gurkha Rifles, was killed in an assault on their base in Helmand province in the early hours of July 13 last year.
He died along with Major James Joshua Bowman and Corporal Arjun Purja Pun.
Their coroner at the inquest in Trowbridge, Wiltshire, yesterday ruled that they were unlawfully killed by a "rogue" Afghan colleague in the Afghan National Army (ANA).
Jonathan Laidlaw QC, representing the family of Lt Turkington, told Brigadier Richard Felton, the commander of Taskforce Helmand at the time, they were concerned that no steps had been taken prior to the attack to prepare the troops for the threat from ANA soldiers.
Brig Felton responded: "The threat wasn't there; there was no evidence for the threat. We had been living cheek-by-jowl with the ANA for four years with no incident."
Brig Felton added that the only similar incident to occur had involved the Afghan National Police but he said that this was not relevant as they were a "different organisation" from the ANA.
Brig Felton said it was not possible to establish rules for coping with every element of risk in a war zone, including that of an internal threat from embedded ANA soldiers.
He told the inquest that the issue of a member of the ANA turning on British troops had not been considered high risk.
Wiltshire Coroner David Ridley recorded verdicts of unlawful killing for all three soldiers and said: "I am satisfied that all three were killed as a result of the actions of the ANA."
Mr Ridley ruled that he saw no evidence of any breaches of the Army's obligations under the European Convention for Human Rights in its obligations to protect the soldiers.
Shooter Talib Hussein had waited until the early hours of July 13 to mount his deadly attack.
The inquest heard that Hussein used an Afghan-issue light machine-gun, an M16 and a grenade launcher during the assault, which he left behind after fleeing.
No-one saw Hussein escape the base afterwards, but it is believed he climbed over a wall.