U.S. President Barack Obama said he has ordered the Pentagon to "spare no effort" in its investigation into the March 11 shooting of 16 Afghan villagers, allegedly by a U.S. Army soldier.
Speaking at the White House, Obama called the incident "heartbreaking" and said it does not reflect American values or represent the U.S. military. He vowed that the perpetrator will be prosecuted with the "full force of the law."
"I've directed the Pentagon to make sure that we spare no effort in conducting a full investigation," Obama said. "I can assure the American people and the Afghan people that we will follow the facts wherever they lead us, and we will make sure that anybody who was involved is held fully accountable with the full force of the law."
His comments came as reports said the White House was discussing whether to accelerate the drawdown of U.S. troops from the country. "The New York Times" reported that a proposal to bring home an additional 20,000 troops in 2013 is being weighed.
Obama again insisted on March 13 that U.S. strategy and the 2014 final withdrawal date won't change.
"Make no mistake, we have a strategy that will allow us to responsibly wind down this war," he said. "We are steadily transitioning to the Afghans, who are moving into the lead. And that is going to allow us to bring our troops home."
The fallout over the March 11 shootings escalated on March 13 with the death of an Afghan soldier who was guarding an Afghan government delegation on a visit to one of the villages where the killings occurred.
A Kandahar Province police official, General Abdul Razaq, said the soldier was killed when suspected militants opened fire on the group.
The delegation, which included two of President Hamid Karzai's brothers and other senior officials, was attending a memorial service in a mosque for victims when the shooting started.
One of the president's brothers, Qayum Karzai, said the members of the delegation, which also included Kandahar Governor Tooryalai Wesa and Minister of Border and Tribal Affairs Asadullah Khalid, were safe and had returned to the city of Kandahar.
The U.S. military is holding an army staff sergeant in custody for his alleged role in the March 11 killings in two villages close to his base in Kandahar's Panjwai district.
Karzai has said that nine of the 16 killed were children, and three were women.
U.S. officials have identified the suspect as a married, 38-year-old father of two who was trained as a sniper. U.S. Defense Secretary Leon Panetta suggested that the suspect could face the death penalty in a military trial.
The killings have caused outrage in Afghanistan but so far have not sparked the kind of violent protests seen last month after it emerged that American soldiers had burned copies of the Koran and other Islamic texts at the Bagram airfield. U.S. officials described those burnings as an erroneous case of disposal.
Hundreds of university students staged a protest in the eastern city of Jalalabad in reaction to the shooting spree. The students shouted, "Death to America!" and, "Death to the soldier who killed our civilians!"
Some protesters called for a public trial of the soldier; others burned an effigy of Obama.
"We don't want any strategic partnership with the foreign troops," protester Dadullah Khan said. "Afghans are independent people. We want to live independently and we don't want to live under any country's colonization. So once again we condemn the Kandahar incident with the strongest words and urge the authorities to put the criminal to trial."
Taliban spokesman Zabiullah Mujahid said in a statement sent to reporters on March 13 that the soldier should be tried as a war criminal and executed by the victims' relatives.
Obama on March 12 expressed his shock and sadness and extended his condolences to the families of the victims. But he said the international community should not perform a rushed withdrawal from Afghanistan.
"What we don't want to do is to do it in a way that is just a rush for the exits," Obama said. "We have got hundreds of advisers in the civilian areas as well. We have got huge amounts of equipment that have to be moved out. We have got to make sure that the Afghans can protect their borders and prevent Al-Qaeda coming back. So we have to do it in a responsible way."
U.S. and other foreign forces are due to withdraw from Afghanistan by the end of 2014, and U.S. and Afghan officials have been negotiating a pact on the long-term presence of U.S. troops in the country.
With AP, AFP, Reuters, and dpa reporting