Top leaders of Afghanistan’s Taliban were holding discussions on Wednesday about how to respond to a US drone strike in Kabul that the United States said killed al Qaeda leader Ayman al-Zawahiri, three sources in the group said. The United States killed Zawahiri with a missile fired from a drone while he stood on a balcony at his Kabul hideout on Sunday, US officials said, the biggest blow to the militants since Osama bin Laden was shot dead more than a decade ago. The Taliban have not confirmed Zawahiri’s death. Officials of the Islamist group, long-time allies of al Qaeda, initially confirme…