Accountability is sought for an air attack that killed 22 people.

Taliban assault comes two weeks before presidential election.

Attack occured in one of Kabul's most heavily guarded districts.

Government officials said to be weighing their response to airstrike.

Says U.S. may pull all of its troops out of his country by the year's end if security agreement is not in place.

Asmatullah Shaheen and two others died in ambush near Afghan border.

Sixty-five detainees have been released from Bagram prison.

U.S. presence discussed as Afghan gov't holds talks with Taliban.

Washington officials classify move as "a major step backwards."