WikiLeaks has released graphic video of a US military Apache helicopter strike in Baghdad three years ago in which two Reuters' employees and a number of other people were killed.
The gunsight footage includes audio conversations between Apache pilots and ground controllers in which they mistakenly identify the men in a Baghdad street as armed insurgents and ask for permission to open fire.
Wikileaks said that it had obtained the video "from a number of military whistleblowers" and decrypted it.
It posted the video at collateralmurder.org.
The July 2007 footage shows an aerial view of a number of men on a Baghdad street including two later identified as Reuters employees Namir Noor-Eldeen and Saeed Chmagh.
At least two individuals in the video appear to be carrying weapons but most are unarmed.
WikiLeaks co-founder Julian Assange spoke about why he released the video.
"We want to show people what modern war is like, this video includes very important elements of modern war", he told the Alyona news show.
"It shows you corruption or debasement of the pilots' characters and their involvement with people on the ground".
"Every action (the pilots) take to kill people, they clear with their commanders first, they ask for permission to attack, to engage".
Camera 'mistaken' for RPG
The Apache pilots also appear to mistake a camera carried by one of the Reuters employees as a rocket-propelled grenade launcher or RPG.
At one point, the Apache pilots tell controllers they have spotted "five to six individuals with AK-47s" and ask for permission to "engage."
The Apache pilots open fire with the helicopter's cannon after which one says there are a "bunch of bodies lying there."
"Look at those dead bastards," one says. Another replies: "Nice."
One of the pilots urges a wounded man to "pick up a weapon" so he can justify opening fire again.
Wounded fired on again
Shortly after the initial shooting, a van pulls up to pick up the dead and wounded and is fired upon by the Apaches.
Two children in the van were injured and evacuated by US ground troops who arrived later on the scene.
A US military official did not dispute the authenticity of the video but said it "doesn't give new information, it just gives footage.
"Since 2007, we acknowledged everything that's in the video," the official said. "We acknowledged that the strike took place and that there were two Reuters employees (killed)."
"We know that two kids were injured," the official said.
'RPG in the video is real'
"The RPG in the video is real," the official added. "We had insurgents and reporters in an area where US forces were about to be ambushed.
"At the time we weren't able to discern whether (the Reuters employees) were carrying cameras or weapons," the official said.
In a statement, Reuters news editor-in-chief David Schlesinger said "the deaths of Namir Noor-Eldeen and Saeed Chmagh three years ago were tragic and emblematic of the extreme dangers that exist in covering war zones.
"The video released today via Wikileaks is graphic evidence of the dangers involved in war journalism and the tragedies that can result," he said.
WikiLeaks, run by Sunshine Press, describes itself as a "non-profit organization funded by human rights campaigners, investigative journalists, technologists and the general public."
The release of the video comes shortly after WikiLeaks released a Pentagon report that cited the whistleblower site as a possible security threat to US troops.
The 2008 report by the US Army Counterintelligence Center said WikiLeaks poses a potential danger to safeguarding troops, protecting sensitive information, and "operational security."
Following the release of the video, Clothilde Le Coz of media rights group Reporters Without Borders urged the Pentagon to show "more transparency" about the shooting and called on the Obama administration to "show its commitment to justice."
