WASHINGTON — President Barack Obama's choice to lead U.S. and NATO troops in Afghanistan appeared on Capitol Hill Tuesday and promised more precise attacks against Taliban and al Qaida targets that would reduce the civilian causalities that are eroding Afghan support for the coalition.

Army Lt. Gen. Stanley McChrystal, the Special Forces commander, appeared before the Senate Armed Services Committee as part of his confirmation, which could come as early as Thursday.

"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," he said.

McChrystal pledged to reexamine U.S. tactics and rules of engagement in Afghanistan.

So far, the Obama administration has pledged to send an additional 17,500 troops and 4,000 trainers, many to southern Afghanistan to take on a resurgent Taliban. Many of those forces are arriving now. There currently are 54,000 U.S. troops in Afghanistan.

McChrystal, a former Special Operations command commander, also answered questions about military detainee operations. In that post, he was in charge of detainees captured by his forces in Afghanistan and Iraq. McChrystal agreed with Sen. Lindsey Graham, R-S.C., an Air Force Reserve lawyer who said that the military needs a comprehensive strategy for detainees.

McChrystal stressed he never endorsed abuse of detainees, "and I never will."

While senators conceded that the U.S. strategy in Afghanistan remains unclear &mdash and could fail — their most pointed questions were about McChrystal's role in how Cpl. Pat Tillman's death was reported. Tillman, a star safety for Arizona Cardinals, was killed in a friendly-fire incident in April 2004. The Army initially claimed that he died in an ambush by enemy forces.

McChrystal signed a letter recommending Tillman receive a Silver Star even though there was some question over the circumstances of his death. The general said Tuesday said that he stood by the decision to recommend the Silver Star even though it was a friendly fire incident.

And he said that mistakes made in reporting how Tillman died were not intentional.

But Sen. Jim Webb, D-Va., told McChrystal that the "the Army failed the family." The general agreed and offered his apology.

"We failed the family. I was a part of that and I apologize for that," he said.

McChrystal succeeds Gen. David McKiernan, who was ousted by Defense Secretary Robert Gates ousted last month.

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