By Caren Bohan and Ahmad Nadem
WASHINGTON/KANDAHAR, Afghanistan, March 12 (Reuters) - President Barack Obama said on Monday the massacre of 16 villagers by a U.S. soldier increases his determination to get American troops out of Afghanistan, while a U.S. official said the accused staff sergeant previously had suffered traumatic brain injury.
Sunday's shootings triggered angry calls from Afghans for an immediate American exit. Obama said there should not be a "rush to the exits" for U.S. forces who have been fighting in Afghanistan since 2001 and that the drawdown must be carried out in a responsible way.
The accused U.S. Army staff sergeant walked off his base in the southern province of Kandahar in the middle of night and gunned down at least 16 villagers, mostly women and children.
Defense Secretary Leon Panetta said the death penalty could be sought in the U.S. military justice system against the soldier, whose name has not been publicly disclosed.
Referring to Sunday's massacre, Obama said in an interview with KDKA, a CBS affiliate in Pittsburgh: "It makes me more determined to make sure we're getting our troops home."
"It's time. It's been a decade, and, frankly, now that we've gotten (Osama) bin Laden, now that we've weakened al Qaeda, we're in a stronger position to transition than we would have been two or three years ago," Obama added, referring to the al Qaeda leader killed by U.S. forces last year in Pakistan.
The Army staff sergeant accused in the incident was treated for traumatic brain injury suffered in a vehicle rollover in 2010 during a previous deployment in Iraq, a U.S. official said. The official, speaking on condition of anonymity, said it was premature to state whether there was any link between the brain injury and Sunday's shootings.
Panetta portrayed the shooting as an isolated event that would not alter plans for a gradual, orderly withdrawal of American combat forces by the end of 2014.
"War is hell. These kinds of events and incidents are going to take place, they've taken place in any war. They're terrible events. And this is not the first of those events, and it probably won't be the last," the U.S. defense secretary told reporters on a flight to Kyrgyzstan.
"But we cannot allow these events to undermine our strategy or the mission that we're involved in."
MY LAI COMPARISONS
Obama was pressed in another separate interview with WFTV, an ABC affiliate in Orlando, on whether there were parallels between the killing of 16 Afghan villagers and the notorious 1968 My Lai massacre of the Vietnam War.
"It's not comparable," Obama said.
"It appeared you had a lone gunman who acted on his own," he said of the Afghanistan incident. "In no way is this representative of the enormous sacrifices that our men and women have made in Afghanistan."
Panetta said the goal was to try the case within the U.S. military justice system. Asked whether the death penalty could be considered, Panetta replied: "My understanding is that in these instances that could be a consideration."
Obama and America's NATO partners intend to pull most of their troops out of Afghanistan by the end of 2014, leaving an inexperienced local army in charge. Officials in Washington denied that the killings might alter that schedule.
"I do not believe this incident will change the timetable of a strategy that was designed and is being implemented in a way to allow for the withdrawal of U.S. forces, to allow for their transfer of lead security authority over to the Afghans," White House spokesman Jay Carney told reporters.
Just days before Sunday's attack, Kabul and Washington had made significant progress in negotiations on a strategic partnership agreement that would allow American advisers and special forces to stay in Afghanistan after most foreign combat troops leave at the end of 2014.
But securing a full deal may be far more difficult now. "This could delay the signing of the Strategic Partnership Agreement," an Afghan government official told Reuters.
The attack was the latest incident to ignite Afghan anger at the United States, coming on the heels of U.S. soldiers' burning of copies of the Koran on a NATO base last month, and other incidents that have intensified America's perception problem in Afghanistan.
Panetta, answering questions for the first time about the shooting rampage, said U.S. officials were still uncertain about the motives behind it.
The accused soldier was part of the 2-3 Infantry, 3rd Stryker Brigade Combat Team, from the Lewis-McChord base in Washington state. After serving three tours in Iraq, he arrived in Afghanistan in December and has been at the Belambai base since Feb. 1.
Based on preliminary findings of a U.S. investigation into the incident, Panetta gave this account of the soldier's actions: "He went out in the early morning and went to these homes and fired on these families. And then at some point after that, came back to the forward operating base and basically turned himself in, told individuals what had happened."
U.S. officials, who have rushed to distance the shootings from the efforts of the 90,000-strong U.S. force that over the past year has beaten the Taliban back from much of southern Afghanistan, say an investigation was under way but did not know when it would conclude.
Afghanistan's parliament condemned the killings, saying Afghans had run out of patience with the actions of foreign forces and the lack of oversight. Civilian deaths have long been one of the main sources of tension between Kabul and Washington.
"We have benefited little from the foreign troops here but lost everything - our lives, dignity and our country to them," said Haji Najiq, a Kandahar shop owner.
"The explanation or apologies will not bring back the dead. It is better for them to leave us alone and let us live in peace."
Fury over the killing spree, which brought demands that the United States withdraw earlier than scheduled, could be exploited by the Taliban to gain new recruits.
Anti-Americanism, which boiled over after the Koran-burning incident, might deepen after the Kandahar carnage.
"The Americans said they will leave in 2014. They should leave now so we can live in peace," said Mohammad Fahim, 19, a university student. "Even if the Taliban return to power our elders can work things out with them. The Americans are disrespectful."
The civilian deaths may also force Afghan President Hamid Karzai to harden his stance in the partnership talks to appease a public already critical of his government's performance.
"The Americans are not here to assist us they are here to kill us," said Najibullah, 33, a house painter in Kabul.
"I hate the Americans and I hate anyone who loves them, so I hope there is no long-term partnership between our countries."
The partnership agreement, which Washington and Kabul have been discussing for more than a year, is expected to be a framework for U.S. involvement in Afghanistan after foreign combat troops leave at the end of 2014.
The Kandahar violence came just days after the United States and Afghanistan signed a deal on the gradual transfer of a major U.S.-run detention center to Afghan authorities, overcoming one of the main sticking points in the partnership negotiations.
Afghanistan wants a timeline to take over detention centers and for the United States and NATO to agree to end night raids on Afghan homes as preconditions for signing the pact.
"Incidents such as this underscore the fact that after 10 years of war, it is time to bring our troops home as soon as we responsibly can," said U.S. Representative Adam Smith, whose congressional district includes the home base of the soldier accused in the massacre.
U.S. forces invaded Afghanistan in 2001 to topple the Taliban rulers who had harbored the al Qaeda network responsible for the Sept. 11 attacks of the United States. Kandahar is the birthplace of the Taliban.
The cost of the war has already exceeded $500 billion and more than 1,900 U.S. troops have been killed, with the total number of foreign troops killed approaching 3,000. (Additional reporting by Ahmad Haroon in KANDAHAR, Hamid Shalizi and Mirwais Harooni in KABUL; Susan Cornwell, Missy Ryan, Alister Bull, Matt Spetalnick in WASHINGTON; Michelle Nicols, Louis Charbonneau and Emily Flitter in NEW YORK; Editing by Will Dunham)