U.S. Defense Secretary Leon Panetta arrived in Afghanistan on Wednesday for a two-day visit amid anger among Afghan leaders about a weekend shooting rampage blamed on an American soldier.
Panetta is the first high ranking U.S. official to visit the war zone since the killing spree in Kandahar province on Sunday that left 16 Afghan civilians dead. A U.S. soldier is now in custody in connection with the shootings.
The defense secretary is due to meet with Afghan tribal leaders and government ministers, but his schedule does not include a visit to the area where the killings took place.
His first stop in Afghanistan was at Camp Bastion and the adjoining base Camp Leatherneck, where he was to meet with top U.S. and British military leaders and speak to a group of about 200 troops. From there he will travel to a nearby forward operating base to meet more coalition troops before flying onto Kabul.
His arrival comes a day after Afghan forces came under fire during a funeral for victims of the shooting rampage, while protesters angered by the killings blocked a major highway in the country's southeast.
In Washington, U.S. President Barack Obama said Tuesday that American officials were "heartbroken" by the deaths but had no plans to change course in the decade-old war in Afghanistan.
Sunday's predawn rampage, which left nine children, three women and four men dead in two villages in rural Kandahar province, has added to the strain between Washington and Kabul. Afghan President Hamid Karzai said Tuesday that the killings "caused great pain for the people of Afghanistan,"
Taliban insurgents have vowed to avenge the killings, and gunshots and grenades echoed in the distance as the victims were buried Tuesday.
"While we were in the village of Alokozai for a funeral, praying for a martyr killed in the massacre, we heard close-range, small-arms fire, followed by two rocket-propelled grenades," said Agha Lali, a member of the Kandahar provincial council. "According to my information, two to three Afghan security forces have been injured."
Lali said high-level Afghan officials, including Karzai's brother, a minister and a deputy minister, were attending the funeral when the attacks took place. The targets appeared to be Afghan investigators collecting evidence in the neighboring village of Najibian, where the remaining victims died.
The Taliban have battled U.S. and NATO troops, as well as Afghan government forces, since the 2001 invasion after the September 11 attacks on New York and Washington. After Sunday's killings, they described U.S. troops as "sick-minded American savages." In a statement Tuesday, they said they would take revenge "by killing and beheading Americans anywhere in the country."
A protest in Jalalabad, near the border with Pakistan, drew hundreds of people Tuesday, with demonstrators blocking the highway to Kabul, provincial government spokesman Ahmad Zaii Abdulzai said. The highway was reopened later Tuesday.
The U.S. military says the Army sergeant blamed for the killings acted alone. Two senior military officials told CNN that images from security cameras around his outpost showed the suspect leaving the base alone and returning alone.
The still-unidentified soldier has yet to be charged. He turned himself in to his fellow Americans after the killings and could face the death penalty, Panetta has said. Afghanistan's parliament has demanded a public trial for the suspect, but U.S. officials said they will handle the investigation and prosecution themselves.
The officials have described the suspect as a staff sergeant from an infantry unit assigned to support Special Forces troops in Kandahar province, the Taliban heartland and a leading focus of the U.S.-led counterinsurgency strategy in Afghanistan.
Military authorities have presented a determination of probable cause to allow them to keep the sergeant in detention, an ISAF offficial told CNN.
Investigators are looking into whether alcohol may have been a factor in the attack, though toxicology tests on the suspect were not complete, the two senior military officials said.
The suspect served three tours of duty in Iraq before being deployed to Afghanistan, according to the U.S. military.
During the suspect's last deployment, in 2010, he was riding in a vehicle that rolled over in a wreck, according to a senior Defense Department official, who also spoke on condition of anonymity. After the wreck, the sergeant was diagnosed with traumatic brain injury but was treated and then found fit for duty, the official said.
Speaking at the White House, Obama said he has told Karzai that the United States "takes this as seriously as if it was our own citizens and our own children who were murdered."
"The killing of innocent civilians is outrageous and it's unacceptable. It's not who we are as a country and it does not represent our military," he said. A U.S. military investigation "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," he added.
Allied combat troops are scheduled to leave Afghanistan by 2014, and Obama said the number will be reduced by more than 30,000 by summer's end, matching the number of Americans he sent in after taking office.
"There's no question that we face a difficult challenge in Afghanistan, but I'm confident that we can continue the work of meeting our objectives, protecting our country and responsibly bringing this war to a close," he said.
In other incidents adding to the strain on U.S.-Afghan relations, U.S. commanders condemned a video of a squad of Marines urinating on bodies in January.
Tensions ramped up dramatically in February, after a group of U.S. soldiers burned copies of the Quran, Islam's holy book, that had been seized from inmates at the American-run prison at Bagram Air Base.
American officials from Obama down called the burning an accident and apologized for it, but riots left dozens dead, including six American troops. Hundreds more Afghans were wounded.