JUDY WOODRUFF: A massacre in the middle of the night, Afghan civilians slaughtered as they slept, an American soldier the lone suspect.
U.S. officials struggled to make sense of those stark facts today, as Afghans demanded justice.
Ray Suarez begins our coverage.
RAY SUAREZ: Afghan soldiers were on alert in Kandahar today, stepping up security to prevent revenge attacks. Anti-American rage was boiling after a U.S. soldier allegedly shot and killed 16 Afghans in their homes, nine of them children.
WOMAN (through translator): They killed a child who was 2 years old. Was this child a Taliban? Believe me, I have not seen a 2-year-old Taliban yet.
RAY SUAREZ: Afghan officials said the soldier left a NATO base in Kandahar late Saturday and walked more than a mile to the village of Balandi. They said he burst into three homes, shooting as he went.
According to villagers, the man then gathered up some of the bodies and set fire to them. Then he walked another mile to the village of Alkozai, killing four more Afghans, before returning to the base, where he surrendered and remains in custody.
He was identified as a 38-year-old staff sergeant from Joint Base Lewis-McChord in Washington State who had served three tours in Iraq. His name was withheld until charges are filed.
Meanwhile, U.S. officials condemned the attack. At the U.N. today, Secretary of State Hillary Clinton called the shootings inexplicable.
SECRETARY OF STATE HILLARY RODHAM CLINTON: A full investigation is under way. A suspect is in custody, and we will hold anyone found responsible fully accountable.
This terrible incident does not change our steadfast dedication to protecting the Afghan people and to doing everything we can to help build a strong and stable Afghanistan.
RAY SUAREZ: President Obama called the shootings heartbreaking, but he said he's still proud generally of what U.S. forces have achieved in Afghanistan.
PRESIDENT BARACK OBAMA: It does signal, though, the importance of us transitioning in accordance with my plan, so that Afghans are taking more of the lead for their own security and we can start getting our troops home.
RAY SUAREZ: He had telephoned Afghan President Hamid Karzai on Sunday, offering condolences, but Karzai in turn called the shootings "an assassination that cannot be forgiven."
Afghan anger was palpable on the streets of Kandahar.
MAN (through translator): We demand our government send the soldier to the Afghan courts. We want to live in peace and freedom. We do not want this situation anymore. We want to get free from the hand of the infidels. And we cannot tolerate to be killed by these infidels.
RAY SUAREZ: Feeding on that anger, the Taliban today vowed revenge for what it called an inhumane crime.
Tensions were already high over the burning of Qurans by U.S. troops last month. That led to a week of deadly protests and the killing of half-a-dozen American troops by Afghan soldiers. A month earlier, a video emerged apparently showing four U.S. Marines urinating on Taliban corpses.
Even so, White House officials insisted today these latest killings would not change the mission in Afghanistan and wouldn't force an early withdrawal.
For more on the shooting story, we're joined from Kabul by Associated Press reporter Heidi Vogt.
Has the arrest of the soldier, the regrets and concerns expressed by senior U.S. officials done anything to tamp down the reaction on the Afghan side?
HEIDI VOGT, Associated Press: Well, we have seen a mixture of outrage and some understanding on the part of the Afghan government.
You know, Hamid Karzai had a very exclamatory statement at the beginning, but at the same time we haven't seen any protests today in Afghanistan, which is what a lot of people were worried about. It's unclear if that's as a result of what the Americans have done or if the news is just taking a little while to get out to people.
RAY SUAREZ: Were there already tensions in Afghanistan over how foreign troops accused of crimes in the country are treated?
HEIDI VOGT: Yes, the tensions have really been high recently. It's been -- this year we had in January a video emerge of U.S. Marines urinating on what looked like Taliban corpses, and then, of course, the Quran burnings just a couple weeks ago and the riots that then killed 30 people.
So we already had a really high level of strife going on. We thought that it was starting to subside recently, this week, but this is really ratcheted it up again.
RAY SUAREZ: We know the accused or about-to-be-accused is 38 years old, has been in service for 11 years. Do we know much more about him?
HEIDI VOGT: We do know that he did three tours in Iraq, and this was his first tour in Afghanistan, just arrived in Afghanistan in December and only moved out to this small base in Panjwai district about six weeks ago.
So he's a pretty new arrival to the area where the attack happened.
RAY SUAREZ: Does this crime differ from the kinds of things that have killed Afghan civilians in previous incidents?
HEIDI VOGT: Well, that's a good question because, obviously, it does, right? I mean, this is an unprecedented event, a U.S. soldier just going out of his base, killing 16 people in the dead of the night.
But, to Afghans, it's unclear if it feels so different. These are people who have been dealing with years of airstrikes that have sometimes inadvertently killed civilians, with attacks that they feel are unjustified at times. And, I mean, there was an attack in 2008 that the officials said killed 90 people. And to many Afghans, those feel just as criminal as this most recent attack. And so, for them, it may not feel as different.
RAY SUAREZ: Apart from this most recent incident, have casualties among Afghan civilians been down in general, because, earlier, it had been a major headache for NATO commanders, hadn't it?
HEIDI VOGT: Well, it depends on how you measure it, because Afghan civilian casualties have been rising each year. And in 2011, more Afghan civilians died than in any previous year.
But the majority of those casualties are from insurgent attacks. We're talking about the roadside bombs. We're talking about people who attack in markets and in government buildings. NATO-related casualties have actually gone down in the same time.
RAY SUAREZ: Has there been any questions of how this all happened in the Afghan public? This is quite an unusual thing for one person working on their own to be able to accomplish.
HEIDI VOGT: Yeah, absolutely.
I mean, that's what we have been hearing from the villagers in recent days, people saying, you know, who is this guy? How did he get out? How is someone just wandering around? There have been people saying on both sides, the American and the Afghan side, this must be a crazy man. This must be someone who was drunk or out of his wits somehow.
But there's also conspiracy theories going. There are Afghans who have said, we think this guy must have been ordered to do this. Otherwise, how would he have gotten out of a base? So there is. There's a lot of rumors.
RAY SUAREZ: Does this threaten the negotiations for some sort of approach, some sort of process with the Taliban?
HEIDI VOGT: Well, that's a good question in terms of, it's a very delicate sort of process we're going through right now that involves the Afghan government and the American government trusting each other a lot.
This certainly risks undermining that trust. Also, there's the question of whether this growing anti-American sentiment makes things easier for the Taliban, emboldens them even, and makes them feel like they don't need to come to the negotiating table. And if that's true, it will be much harder to have any sort of talks with them.
RAY SUAREZ: Heidi Vogt of the Associated Press joined us from Kabul.
Good to talk to you.
HEIDI VOGT: Of course.