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(CNN) -- Chilling scenes from a videotape made by insurgents show the work of snipers in Iraq, targeting and killing American troops, taking them down with a single bullet from a high-powered rifle.
The graphic video of 10 sniper attacks was obtained by CNN -- through intermediaries -- from the Islamic Army of Iraq, one of the most active insurgent organizations in Iraq.
In one scene, U.S. soldiers mingle among Iraqi civilians on a city street as a U.S. Humvee with a gunner in its turret stands guard nearby.
From a distance, possibly hundreds of yards away, a sniper watches for his opportunity to strike as a fellow insurgent operates a camera to capture the video for propaganda purposes.
In the video, street sounds mix with male Arabic voices as the sniper and his spotter talk off-camera.
"People are around them," warns the spotter, who seems to be operating the video camera. "Want me to find another place?"
"No, no," comes the reply, "give me a moment."
And then, the crack of gunfire is heard and the soldier in the turret slumps forward.
"Allahu Akbar (God is Great)!" is the exclamation as the sniper's vehicle starts and they slip away.
The deadly tactic is one the U.S. military also uses to take out insurgents.
Retired Gunnery Sgt. Jack Coughlin was one of the top U.S. Marine Corps snipers in Iraq and has written a book about his experiences -- "Shooter: The Autobiography of the Top-Ranked Marine Sniper."
"I have over 60 kills," he told CNN's Gary Tuchman. "We seek out the enemy and eliminate them with precision fire."
Tuchman used Coughlin's critical eye to analyze the Islamic Army of Iraq video.
Coughlin said the time lapse between the sound of the shot and the man getting hit indicates the gunfire is coming from about 300 to 500 yards away and probably from a higher angle.
But Couglin said he's sure this team of at least three people has been trained well because they're so calm.
"They have their stuff wired," he said. "They know what they're doing." (Watch the ex-Marine describe snipers' deadly work -- 2:46)
The 20-year Marine veteran said the kind of body armor worn by troops in combat can be effective against a sniper's bullet, and he added that there are other ways to defend against the horrifying attacks.
"The worst enemy of a sniper is another sniper," Coughlin said. "Our snipers are hunting these guys -- I guarantee you this is happening as we speak."
Coughlin added that, in many cases, the best defense is a good offense.
Still image from an insurgents' video shows U.S. soldiers being targeted by a sniper.