A British Lynx helicopter which crashed in Basra, southern Iraq, last May was shot down by a surface-to-air missile, an investigation has found.
The Ministry of Defence says the Lynx is a "deadly tank-killer".
Five service personnel died when the aircraft plunged into a two-storey house in the centre of the city.
The incident sparked violent clashes between local people and British forces.
Among the dead was Flight Lieutenant Sarah Mulvihill, the first British servicewoman to die in action in Iraq.
Wing Commander John Coxen, Lieutenant Commander Darren Chapman, Captain David Dobson and Marine Paul Collins also died.
Armed Forces Minister Adam Ingram announced the findings of a board of inquiry (BOI) into the crash in a written statement to MPs.
"The key conclusion of the BOI is that the Lynx was shot down by a surface-to-air missile, using a man-portable air defence system, fired from the ground," he said.
Mr Ingram said the board had made seven recommendations which had been acted upon, but would not be made public "in order to protect the security and operational effectiveness of our armed forces".
He also paid tribute to those who died, adding: "Our thoughts are with all their families and friends."
After the crash on 6 May, troops were attacked with guns, stones, petrol bombs and blast bombs.
Mr Ingram said relatives of the personnel had been informed of the board's conclusions.
Inquests into the five deaths will be heard by the Oxfordshire assistant deputy coroner.