President Barack Obama has said that the massacre of 16 villagers by a US soldier raises his determination to get American troops out of Afghanistan, while a US 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 US forces who have been fighting in Afghanistan since 2001 and that the drawdown must be carried out in a responsible way.
The accused US 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 US 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 US forces last year in Pakistan.
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."
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.
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 US involvement in Afghanistan after foreign combat troops leave at the end of 2014.
Without a pact that keeps US advisers or special forces in the country, there is a danger that civil war could erupt again in Afghanistan.
The Kandahar violence came just days after the United States and Afghanistan signed a deal on the gradual transfer of a major US-run detention center to Afghan authorities, overcoming one of the main sticking points in the partnership negotiations.
Afghanistan wants a timeline to take ove
States and NATO to agree to end night raids on Afghan homes as preconditions for signing the pact.
US 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.