Afghan massacre: US soldier 'acted alone' in Kandahar
A US soldier accused of killing 16 Afghan civilians in a night-time rampage acted alone, US officials say.
The Pentagon said in a media briefing that the killings, in the early hours of Sunday, were "tragic" but insisted it was an isolated incident.
White House spokesman Jay Carney said the the shootings would not affect the schedule for US troop withdrawal.
Afghan MPs earlier passed a motion saying civilians have lost patience with foreign troops.
The incident has put more strain on relations between Afghans and foreign forces.
Anti-US sentiment is already high after soldiers burned some copies of the Koran at a Nato base in Kabul last month, sparking deadly riots across the country.
The Taliban has promised revenge attacks for the latest killings. A tribal elder told the BBC that he would not be calling for protests.
Details about the shootings are still unclear, but the American soldier left his base in the southern province of Kandahar in the early hours of Sunday.
He walked into several houses and apparently shot and killed 16 people, mostly women and children.
One witness said she saw the man drag a woman out of her house and repeatedly hit her head against a wall.
A Pentagon spokesman confirmed that the soldier, who is said to be in his 30s with three children, turned himself in to the military authorities after he returned to base.
The spokesman said the soldier's name would not be released while the investigation was going on, but added that there was "every indication" that he had acted alone.
Officials have offered no explanation for the incident, but reports suggest the soldier might have been drunk, or had suffered a nervous breakdown.
ABC Newsquoted an unnamed officialsaying he had suffered a brain injury and marital problems in the past. The authorities have not commented on the claims.
US defence officials said that the soldier was from the conventional army, not special forces, and confirmed that he had completed multiple tours in Iraq but was on his first tour of duty in Afghanistan.
Several reports have identified the soldier as a member of the 2-3 Infantry, 3rd Stryker Brigade combat team, a unit based at Joint Base Lewis-McChord, in the north-western state of Washington.
The base was home to the so-called "kill team", a rogue unit led by Sgt Calvin Gibbs that kept grisly souvenirs of Afghans they killed.
'Difficult and complex'
Nato and US officials have insisted that there would be no change in strategy in Afghanistan after Sunday's attacks.
Nato's Isaf forces plan to withdraw all of its combat forces by the end of 2014. American troops are also following that timetable.
"The focus of our overall strategy is not in reaction to a single event," White House spokesman Jay Carney told reporters on Monday.
Speaking at the United Nations, US Secretary of State Hillary Clinton said the killings underscored that the US had faced a "difficult and complex few weeks" in Afghanistan.
"This terrible incident does not change our steadfast dedication to protecting the Afghan people and doing everything we can to help build a strong and stable Afghanistan," she told reporters.
The killings come at a time when polls suggest Americans are increasingly questioning the point of remaining in Afghanistan.
Asurvey by the ABC News/Washington Postfound that 60% said the war has not been worth the cost, while 54% wanted American troops to leave Afghanistan now.