WASHINGTON - Flanked by the leaders of Afghanistan and Pakistan, President Barack Obama expressed deep U.S. regret Wednesday for civilian casualties in a deadly incident this week in western Afghanistan, promising "every effort" to avoid recurrences in the war against a rising Taliban insurgency.
Obama had a more upbeat and determined tone as he lauded "unprecedented cooperation" between the two neighbors in fighting Taliban and other extremist threats. But he cautioned that success will not come quickly.
"Along the border, where insurgents often move freely, we must work together with a renewed sense of partnership to share intelligence and to coordinate our efforts to isolate, target, and take out our common enemy," Obama said after a day of meetings with Afghan President Hamid Karzai and Pakistani President Asif Ali Zardari.
Obama met separately with Karzai and Zardari, followed by a three-way session that Secretary of State Hillary Rodham Clinton portrayed as an embodiment of a central tenet of the administration's new Afghan war strategy - that Pakistan and Afghanistan are linked problems.
The latest report of Afghan civilian casualties came at an especially awkward time for the administration, which is stepping up its military campaign inside Afghanistan while also seeking to emphasize the importance of nonmilitary efforts to stabilize the country. The U.S. has pledged, for example, a major increase in civilian expertise in farming and other specialties, along with an increase of 21,000 U.S. troops.
Obama's strategy, unveiled in late March, already is threatened by setbacks to his goal of strengthening a shaky Pakistani government, eliminating al-Qaida and Taliban sanctuaries on the Pakistan side of the Afghan border and fighting Afghan government corruption. Claims of U.S. culpability for civilian deaths in Afghanistan are an added burden.
Gen. Jim Jones, Obama's national security adviser, told reporters that the president began his meeting with Karzai by addressing reports that dozens of civilians had been killed by American bombs on Sunday.
Jones said Obama commented "with great sympathy" and expressed regret for the loss of innocent life. Earlier, before her meetings with Karzai and Zardari at the State Department, Clinton said the U.S. "deeply, deeply" regrets the losses.
Both Obama and Clinton stopped short of accepting U.S. blame for the deaths.
Obama told Karzai that investigations "will be pursued aggressively with full intent to discover what in fact did happen, how it happened and how we can make sure that things like that do not happen again. And it was clear that President Karzai was moved by that ... and he thanked the president for starting off the meeting with that expression of condolence."
Karzai did not ask that U.S. airstrikes be suspended or reduced in intensity pending the outcome of the investigation, Jones said.
Nor did Zardari raise an equally sensitive topic on his side of the border - the use of U.S. Predator aircraft to attack extremist targets, Jones said. Pakistanis have strongly protested those attacks, saying they have killed innocent civilians.
In Afghanistan, the U.S. forces commander said it wasn't a certainty that Sunday's deaths were a result of U.S. military action. Gen. David McKiernan said American forces came to the aid of Afghans who may have been ambushed by the Taliban. He said the Taliban beheaded three civilians, perhaps to lure police.
"We have some other information that leads us to distinctly different conclusions about the cause of the civilian casualties," McKiernan said. He would not elaborate.
Karzai, whose public criticism of U.S. airstrikes has grown increasingly indignant, thanked Clinton politely for her concern.
"We appreciate that," Karzai said. "And we hope we can work together toward reducing and eventually completely removing the possibilities of civilian casualties."
The United States has estimated that 80 percent or more or civilian deaths are caused by militants, not U.S. or allied forces, but Obama and his advisers say they know the corrosive effect the airstrikes have on civilian support for the military mission.
In his remarks at the White House, Obama emphasized the progress he said was achieved in the Washington meetings.
"We have advanced unprecedented cooperation," Obama declared. "We will work for the day when our nations are linked not by a common enemy but by a shared peace and prosperity."
Veteran diplomat Richard Holbrooke, the administration's point man for Afghanistan and Pakistan and a participant in the meetings, was upbeat in brief remarks after Obama summarized the day's talks. "It was a day that exceeded our expectations," Holbrooke said. "We turned a corner" in improving coordination.
Gathering the three leaders together at one table, along with lower-level officials from the three countries, "reflects the kind of concrete cooperation and detail that is going to ultimately make a difference in improving opportunity and democracy and stability in Pakistan and in Afghanistan," Obama said.
The stakes couldn't be higher, he said.
"We have learned time and again that our security is shared," the president said. "It is a lesson that we learned most painfully on 9/11, and it is a lesson that we will not forget."
The president said all three governments must cooperate in fighting insurgents who control parts of Pakistan and Afghanistan and must "deny them the space" to threaten local residents - or Americans.
Earlier in the day, Clinton told reporters that Karzai and Zardari made specific commitments of how they would increase the fight against militants. She wouldn't name their promises yet, but said the talks were "producing some very promising early signs" of greater cooperation.
"I am very optimistic that this process is making a difference," she said in remarks in the White House briefing room.
Associated Press writers Anne Gearan, Jennifer Loven and Ben Feller contributed to this report.