JUDY WOODRUFF: But first: civilian casualties in the Afghan war.
And to Margaret Warner.
MARGARET WARNER: Afghan anger over foreign forces causing civilian deaths has become an especially sensitive issue in the last year. The latest flash point came Sunday, an airstrike here along the border of Uruzgan and Daykundi provinces.
NATO said its planes attacked three vehicles, thinking they carried insurgents. Instead, Afghan officials said 27 civilians were killed, including four women and a child. Twelve others were wounded.
SHUKRIA BARAKZAI, member of Afghan parliament: It's very difficult for us, for the people of Afghanistan, to find answer why civilian people are dying. We don't have any answer for this.
MARGARET WARNER: It was the third such incident this month, and the worst since U.S. pilots bombed hijacked fuel tankers last September. Afghan leaders estimated 30 to 40 civilians were killed then, with scores more wounded.
Today, the country's council of ministers called the airstrike unjustifiable. And a government spokesman demanded greater restraint by NATO forces. The overall NATO commander, U.S. Army General Stanley McChrystal, quickly apologized to Afghan President Hamid Karzai. He also issued a new warning to his staff.
LT. GEN. NICK PARKER, deputy commander of ISAF: General McChrystal had all his junior commanders in this morning. And he made it absolutely clear to them that he expects commanders on the ground to make these difficult judgments as clearly and as carefully as they possibly can in order to minimize the risk of casualty to civilians.
We're clear that, if we kill the people that we're actually trying to protect, our credibility is undermined.
MARGARET WARNER: The airstrike in Uruzgan was unrelated to the ongoing offensive in Marjah in southern Helmand Province. U.S. Marine commanders say they have gone to great lengths to avoid civilian casualties there, even if it means moving more slowly.
So far, NATO forces say, 16 Afghan civilians have died in the Marjah fighting, along with 13 NATO troops and 120 insurgents. The emphasis on cutting civilian losses, including new rules of engagement and quick apologies, goes back to last summer.
General McChrystal outlined the strategy at his Senate confirmation hearing.
GENERAL STANLEY MCCHRYSTAL, U.S. commander in Afghanistan: This is a critical point. It may be the critical point. This is a struggle for the support of the Afghan people. Our willingness to operate in ways that minimize casualties or damage, even when doing so makes our task more difficult, is essential to our credibility.
MARGARET WARNER: Today, in Washington, Joint Chiefs Chairman Admiral Mike Mullen was asked why, with the new rules of engagement, civilians are still being killed.
ADMIRAL MICHAEL MULLEN, joints chiefs chairman: I think it's just very -- it's a very difficult environment. It's -- it's tough terrain. It's tough to know. And these are split-second decisions that -- that commanders in combat on the ground have to make.
MARGARET WARNER: Defense Secretary Robert Gates said the reasons for yesterday's strike are being investigated.
ROBERT GATES, U.S. secretary of defense: General McChrystal is doing everything humanly possible to avoid civilian casualties. But it is also a fact that the Taliban mingle with civilians. They use them for cover, which obviously complicates any decision process by a commander on the ground, in knowing whether he's dealing with the Taliban or innocent civilians or a combination of the two.
I'm -- I'm not defending it at all. I'm just saying that -- that these kinds of things in many respects are inherent in a war. It's what makes war so ugly.
MARGARET WARNER: Still, on Saturday, President Karzai said NATO is not yet doing enough.
HAMID KARZAI, president of Afghanistan (through translator): No Afghan family should suffer from this. Until we reach this goal, we will continue our efforts, our criticism, and we will raise our voices, despite all the efforts to prevent civilian casualties, until we reach the point where there are no civilian casualties.
MARGARET WARNER: U.N. numbers show that 2,400 Afghan civilians were killed in 2009, the most since the war began in 2001. But the great majority were caused by insurgents, and deaths caused by NATO troops dropped nearly 30 percent.