Washington ? Pentagon officials worry that outrage over a video purporting to depict Marines urinating on Taliban corpses will tarnish the reputation of the entire military. Some also fear it could undermine prospects for exploratory Afghan peace talks.

After roundly condemning the Marines’ alleged behavior, Defense Secretary Leon Panetta and top military leaders on Thursday promised a full investigation and sought to contain the damage at home and abroad.

Panetta also said the incident could endanger the prospects for peace talks, although the Obama administration and the Taliban each voiced readiness Thursday to try negotiations while pledging to carry on the military conflict until their rival objectives are met. The separate statements by senior American and Taliban officials illustrated the improved environment for Afghan reconciliation efforts as well as the daunting task ahead.

The Naval Criminal Investigative Service, the law enforcement arm of the Navy, is heading the main inquiry, which is expected to weigh evidence of violations of the U.S. military legal code as well as the international laws of warfare. Separately, the Marine Corps is doing its own internal investigation.

By Friday, the NCIS had identified all four of the Marines appearing in the video and interviewed at least two of them. At the time they were filmed urinating on the bodies, the four were members of the 3rd Battalion, 2nd Marines, which fought in the southern Afghan province of Helmand for seven months before returning to their home base at Camp Lejeune, N.C., last September.

Two of the four, plus the commander of the battalion, had moved on to other assignments before the video appeared on the Internet, according to Marine Corps officials who spoke on condition of anonymity in order to discuss an active investigation. The Marines’ names have not been made public.

The commandant of the Marine Corps, Gen. James Amos, was preparing to name an officer to serve as the “convening authority” — the officer who would be tasked with considering a course of action in light of any charges that might be brought against the Marines as a result of the NCIS investigation. Charges could lead to courts-martial or lesser administrative disciplinary actions.

Even the emergence of the Internet video depicting Marines urinating on what appear to be Afghan corpses didn’t seem to immediately set back movement toward exploratory negotiations with the Taliban. Asked about possible implications for peace talks, Secretary of State Hillary Rodham Clinton said Thursday the U.S. remained strongly committed to supporting Afghan efforts.

Panetta, however, said the incident could endanger the 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, adding it’s important for the U.S. 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.”

Before he left Washington for his troop visit in Fort Bliss, Panetta called President Hamid Karzai to promise a full investigation of the video affair and condemned the Marines’ behavior as “entirely inappropriate.”

As the video spread across the Internet in postings and re-postings, U.S. officials joined with Afghans in calling it shocking, deplorable, inhumane and a breach of military standards of conduct. It shows men in Marine combat gear standing in a semicircle urinating on the bodies of three men in standard Afghan clothing, including one whose chest was covered in blood.

It’s not certain whether the dead were Taliban fighters, civilians or someone else.

The incident will likely further hurt ties with Karzai’s government and complicate negotiations over a strategic partnership arrangement meant to govern the presence of U.S. troops and advisers in Afghanistan after most international combat troops withdraw by the end of 2014.

Anti-American sentiment is already on the rise in Afghanistan, especially among Afghans who have not seen improvements to their daily lives despite billions of dollars in international aid. They also have deplored the accidental killing of civilians during NATO airstrikes and argue that foreign troops have culturally offended the Afghan people, mostly when it comes to activities involving women or the Quran, the Muslim holy book.

Pentagon officials said the criminal investigation would likely look into whether the Marines violated laws of war, which include prohibitions against photographing or mishandling bodies and detainees. There’s also the issue of violations to the U.S. Uniform Code of Military Justice, which governs conduct.

Karzai called the video “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.

The chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, said he was deeply disturbed by the video and worried that its effects would spread beyond just the Marine Corps.

“Actions like those are not only illegal but are contrary to the values of a professional military and serve to erode the reputation of our joint force,” Dempsey said.

On the streets of Afghanistan, the reaction was cool.

“If these actions continue, people will not like them (the Americans) anymore and there will be uprising against them,” Mohammad Qayum, said while watching a television news story about the video that was airing in a local restaurant in Kabul.

Ahmad Naweed, a shopkeeper in Kandahar, the birthplace of the Taliban insurgency, said, “On the one hand, the Americans present themselves as friends of Afghanistan and … they also try to have peace talks with the Taliban. So we don’t know what kind of political game they are playing in Afghanistan.”

Associated Press writers Pauline Jelinek in Washington, Deb Riechmann in Kabul and Juan Carlos Llorca in El Paso, Texas, contributed to this report.