Updated 10:33 PM ET
WASHINGTON - The Marines seen in an internet video that purports to show them standing around and urinating on Taliban corpses in Afghanistan have been identified as members of a Marine Corps sniper team, reports CBS News correspondent David Martin.
An official told the Associated Press that the Marine Corps has identified by name at least two of the four Marines the video.
All four were members of the 3rd Battalion, 2nd Marines, which returned to its home base in North Carolina last fall after a tour in Afghanistan. The 1,000 man battalion lost seven men killed in action and is now back home at Camp Lejuene in North Carolina, where more than just the four who showed their faces could be liable to criminal charges.
The official who spoke to the AP said that at least some of the four Marines are no longer in that battalion. He provided no other details.
Defense Secretary Leon Panetta on Thursday condemned as "utterly deplorable" the actions in the video. He said such behavior is "entirely inappropriate for members of the United States military" and those responsible will be held accountable.
Panetta said he had ordered the Marine Corps and Marine Gen. John Allen, the top commander of the NATO-led forces in Afghanistan, to fully investigate.
The Marine Corps said Wednesday it would investigate the YouTube video but had not yet verified its origin or authenticity. The case has been referred to the Naval Criminal Investigative Service, the Navy's worldwide law enforcement arm.
The video, posted on the Internet, shows men in Marine combat gear, standing in a semi-circle over three bodies. It is not clear whether the dead were Taliban or civilians or someone else. The title on the posting called them Taliban insurgents but it was unclear who added that title, Marine Corps officials in Washington said.
If the video turns out to be authentic, those involved could face court martial proceedings for violating U.S. military rules which specifically forbid "photographing or filming... human casualties" - regardless of whether the Americans were actually urinating.
Because the Marines in the video are no longer in Afghanistan, there are questions about how old the video is exactly.
The reaction from Afghanistan was angry.
Afghan President Hamid Karzai condemned the video as "completely inhumane." The Afghan Defense Ministry called it "shocking." And the Taliban issued a statement accusing U.S. forces of committing numerous "indignities" against the Afghan people.
"First they killed the Afghans with mortars, and they then urinated on their bodies," Taliban spokesman Zabiullah Mujahid said. "We strongly condemn this inhumane action by the wild American soldiers."
Panetta said the actions, if true, were inexcusable.
"I have seen the footage, and I find the behavior depicted in it utterly deplorable. I condemn it in the strongest possible terms," Panetta's statement said. "Those found to have engaged in such conduct will be held accountable to the fullest extent."
The video came to light at a delicate time in relations among the United States, Afghanistan's elected government and the Taliban insurgency fighting for both territorial control and cultural and religious preeminence in Afghanistan.
The U.S. is trying to foster peace talks between the Karzai government and the Pakistan-based Taliban high command, and has made unprecedented offers to build trust with the insurgents, including the planned opening of a Taliban political office to oversee talks.
One of the largest obstacles to peace discussions has been widespread Afghan contempt for U.S. military tactics that many both Taliban sympathizers and not see as heavy-handed. Opposition to the U.S. and NATO military presence in Afghanistan usually centers on civilian casualties from military engagement, although the vast majority of those deaths are caused by the insurgents.
Panetta said the incident could endanger U.S.-Afghan-Taliban peace talks.
"The danger is that this kind of video can be misused in many ways to undermine what we are trying to do in Afghanistan and the possibility of reconciliation," Panetta said at Fort Bliss, Texas. He said it is important for the United States to move quickly to "send a clear signal to the world that the U.S. will not tolerate this kind of behavior and that is not what the U.S. is all about."
Speaking to CBS News' Ahmad Mukhtar on the phone Thursday, Mujahid, the Taliban spokesman, strongly reiterated that talks with the Americans have not begun, but he said if they do, the video of the alleged desecration "will not harm" the dialogue.
Although the video purports to show Taliban fighters, not civilians, it is likely to resonate with those opposed to the U.S. presence and to peace with the U.S.-backed Karzai government. In his statement, Karzai called on the U.S. military to punish the Marines.
The NATO-led security force in Afghanistan released a statement Thursday saying, "This disrespectful act is inexplicable and not in keeping with the high moral standards we expect of coalition forces."
The actions "appear to have been conducted by a small group of U.S. individuals, who apparently are no longer serving in Afghanistan," the International Security Assistance Force said. The statement did not identify the personnel or explain why the ISAF thought they had left the country.
McCain, the top Republican on the Senate Armed Services Committee, called the Marine Corps one of America's strongest institutions and said its image has apparently been tarnished by "a handful of obviously undisciplined people."
"There should be an investigation and these young people should be punished," McCain said Thursday on "CBS This Morning."
On Wednesday, the Council on Islamic-American Relations, a prominent Muslim civil rights and advocacy group based in Washington, protested the video in a letter to Panetta.
"We condemn this apparent desecration of the dead as a violation of our nation's military regulations and of international laws of war prohibiting such disgusting and immoral actions," the group wrote.
"If verified as authentic, the video shows behavior that is totally unbecoming of American military personnel and that could ultimately endanger other soldiers and civilians," the letter said.