NEW : Karzai : Civilian deaths cause serious tensions between Afghanistan and Pakistan . Karzai calls casualties unacceptable . Afghan president says such strikes ca n't be a ` ` even if NATO bases are attacked '' NATO says it will no longer use airstrikes on civilian homes if ` ` other options '' are available . The shift comes after an airstrike last week in Kabul province that killed 18 people .
NEW : Karzai : Civilian deaths cause serious tensions between Afghanistan and Pakistan . Afghan president says such strikes ca n't be a ` ` even if NATO bases are attacked '' NATO says it will no longer use airstrikes on civilian homes if ` ` other options '' are available . The shift comes after an airstrike last week in Kabul province that killed 18 people .