The death of a UK soldier when a US pilot fired on his convoy in Iraq was unlawful, a coroner has ruled.
The "friendly fire" incident which killed Lance Corporal of Horse Matty Hull, 25, was a criminal act, he said.
Andrew Walker said the 2003 death was "entirely avoidable" and L/Cpl Hull's widow said the verdict was "right".
The Ministry of Defence apologised for a delay in releasing film from the US A-10 plane. The Pentagon offered the Hull family its "deepest sympathies".
In delivering his narrative verdict, Mr Walker said: "The attack on the convoy amounted to an assault.
"It was unlawful because there was no lawful reason for it and in that respect it was criminal."
Four other soldiers were injured in the attack near Basra
No American witnesses gave evidence at the inquest and the coroner was critical of the failure of the US authorities to co-operate.
"I believe that the full facts have not yet come to light," said the Oxford assistant deputy coroner.
The US pilots should have flown lower to confirm identities before opening fire, he added.
"I don't think this was a case of honest mistake."
Speaking after the verdict, widow Susan Hull said she felt a great sense of relief that it was over and it had confirmed that her husband's death was "entirely avoidable".
"I think all of our family feel it was the right verdict. It was what we'd waited four years to hear."
She said she was now prepared to "draw the line" on the event.
"It's been a long and painful time and we need to move forward."
But she said the lack of co-operation from the US was "very disappointing".
Afterwards, lawyer Geraldine McCool said the verdict did not suggest there would be a prosecution of the US pilot and the Hull family would not be calling for one.
The Ministry of Defence said it was "very sorry for confusion and upset" caused by the handling of the US cockpit tape.
The recording was not initially shown to the inquest, but the US authorities only agreed for it to be released after the footage was leaked to the Sun newspaper.
An MoD spokesman said: "This inquest has highlighted the need for a more coherent approach to the management of documentation and evidence."
He said a team has been set up to liaise with coroners and bereaved families and to ensure documents are made available quickly to inquests.
The Hull family believes key information was blacked out of a US Friendly Fire Investigation Board Report given to the coroner investigating his death.
Mrs Hull had directly appealed to US President George W Bush to give the coroner the information.
Constitutional affairs minister Harriet Harman, who met with US diplomats in London ahead of the inquest, said she shared the "frustration" at their failure to send witnesses.
"I explained that this was not a criminal court, nobody could be found guilty and sent to prison, it is simply asking questions and requiring answers," she said.
"But I am afraid that they weren't prepared to change their position."
In a statement the US defence department said its own investigation concluded the death was a "tragic accident".
The statement said the US shared all the information from its inquiry with the MoD, except those parts that had to be withheld for "security, privacy or other reasons".
"The investigation determined that the incident took place in a complex combat environment, the pilots followed applicable procedures," it said.
L/Cpl Hull, who was from the Household Cavalry, died from multiple injuries inside his blazing Scimitar tank despite efforts by colleagues to save him.
Four other soldiers travelling in the convoy of light armoured vehicles were also injured in the incident on 28 March 2003 near Basra.
Shadow defence secretary Liam Fox called for improvements in training and better identification of allied vehicles.
"It's incumbent upon the British and American defence departments to ensure that all cautions possible are taken to avoid all future tragedies of this kind," he said.