LOS ANGELES, Oct. 5 — Videos showing insurgent attacks against American troops in Iraq, long available in Baghdad shops and on Jihadist Web sites, have steadily migrated in recent months to popular Internet video-sharing sites, including YouTube and Google Video.
Many of the videos, showing sniper attacks against Americans and roadside bombs exploding under American military vehicles, have been posted not by insurgents or their official supporters but apparently by Internet users in the United States and other countries, who have passed along videos found elsewhere.
Among the scenes being viewed daily by thousands of users of the sites are sniper attacks in which Americans are felled by snipers as a camera records the action and of armored Humvees or other military vehicles being hit by roadside bombs.
In some videos, the troops do not appear to have been seriously injured; in one, titled “Sniper Hit” and posted on YouTube by a user named 69souljah, a serviceman is knocked down by a shot but then gets up to seek cover. Other videos, however, show soldiers bleeding on the ground, vehicles exploding and troops being loaded onto medical evacuation helicopters.
At a time when the Bush administration has restricted photographs of the coffins of military personnel returning to the United States and the Pentagon keeps close tabs on videotapes of combat operations taken by the news media, the videos give average Americans a level of access to combat scenes rarely available before, if ever.
Their availability has also produced some backlash. In recent weeks, YouTube has removed dozens of the videos from its archives and suspended the accounts of some users who have posted them, a reaction, it said, to complaints from other users.
More than four dozen videos of combat in Iraq viewed by The New York Times have been removed in recent days, many after The Times began inquiries.
But many others remain, some labeled in Arabic, making them difficult for American users to search for. In addition, new videos, often with the same material that had been deleted elsewhere, are added daily.
Russell K. Terry, a Vietnam veteran who founded the Iraq War Veterans Organization, said he had mixed feelings about the videos.
“It’s unfortunate there’s no way to stop it,” Mr. Terry said, even though “this is what these guys are over there fighting for: freedom of speech.”
One YouTube user, who would not identify himself other than by his account name, facez0fdeath, and his location, in Britain, said by e-mail that he posted a video of a sniper attack “because I felt it was information the U.K. news was unwilling to tell.”
“I was physically sickened upon seeing it,” he said, adding, “I am wholly opposed to any form of censorship.”
The video he posted, which had been viewed more than 33,000 times, was removed earlier this week.
Another YouTube user, who said he was a 19-year-old in Istanbul and who posted more than 40 videos of Iraq violence, said via e-mail that “anti-war feelings and Muslim beliefs (the religion of peace) motivates me.”
Neal O. Newbill, a freshman at the University of Memphis who viewed some of the YouTube videos and posted comments on them, said in an interview that he was enraged by the recorded chants of “Allahu Akbar,” Arabic for “God is great,” that follow some of the sniper attacks.
But Mr. Newbill added that he was awed by the size of the blasts from the improvised explosive devices, or I.E.D.’s, used against American vehicles. A son, nephew and grandson of American veterans, Mr. Newbill said he had sought out the videos, searching on YouTube for “I.E.D.,” “because I like watching stuff blow up.”
The Web sites also contain a growing number of video clips taken by American soldiers. One shows the view from the back of a truck containing several members of a platoon, whose vehicle then hits an I.E.D. and is turned on its side. A few videos also show American servicemen or private security guards firing at attackers, and one shows an American rocket-propelled grenade hitting a building from which insurgents are firing.
A spokesman for United States Central Command, which oversees troops in Iraq, said the military was aware of the use of common Internet sites by both insurgent groups and American military personnel.
“Centcom is aware we are facing an adaptive enemy that uses the Internet as a force multiplier and as a means of connectivity,” Maj. Matt McLaughlin, the spokesman, said by e-mail.
While posting of Web logs, pictures and videos by American troops is subject to military regulations, Major McLauglin said, “Al Qaeda uses the Internet and media to foster the perception that they are more capable than they are.”
Some of the videos are obvious propaganda, with Arabic subtitles and accompanying music, while others simply have scenes without sound or graphics. They appear to be real, though the results of attacks are not always clear.
One frequently posted video shows individual photographs of several hundred American soldiers allegedly killed by a Baghdad sniper referred to as Juba. But a television news report from the German weekly Der Spiegel that also has been posted on the video sites shows an interview with one American soldier whom the insurgent group claimed to have killed but whose protective vest stopped the sniper’s bullet.
Geoffrey D. W. Wawro, director of the Center for the Study of Military History at the University of North Texas and a former instructor at the United States Naval War College, said the erosion of the command structure of terrorist and insurgent groups had led them to increase their reliance on the Internet and videos to gain recruits.
American troops, too, have always sent snapshots home from the front, Mr. Wawro said, and digital pictures and video are simply a new incarnation of that.
“This is how the new generation does things,” he said.
“It results in a continued trivialization of combat and its effects,” Mr. Wawro added, “but no one feels completely comfortable saying, Don’t do it.”
YouTube does feel comfortable saying so, however, as does Google Video. Both have user guidelines that prohibit the posting of videos with graphic violence, a measure that spokeswomen for each service said was violated by many of the Iraq videos.
Julie Supan, senior director of marketing for YouTube, said the company removed videos after they were flagged by users as having inappropriate content and were reviewed by the video service.
In an e-mail message, Ms. Supan said that among the videos removed were those that “display graphic depictions of violence in addition to any war footage (U.S. or other) displayed with intent to shock or disgust, or graphic war footage with implied death (of U.S. troops or otherwise).”