Use of drones is most controversial in Pakistan’s tribal areas The United States tracked al-Qaida efforts to find a defence against drone strikes, documents leaked by former national security contractor Edward Snowden show. The Washington Post reported Tuesday the leaked classified documents suggest the terrorist group has had no success so far, with no evidence any drones have been shot down or destroyed. The documents include a report titled \"Threats to Unmanned Aerial Vehicles\" that contains intelligence on al-Qaida\'s efforts from 2006 on. Snowden, a former contractor for the National Security Agency, faces criminal charges in the United States. He has been given temporary asylum in Russia. US drone strikes have killed about 3,000 people since 2003 in Pakistan, Yemen, Somalia and other countries, the Post said. While the drones target members of al-Qaida and similar groups, hundreds of civilians have been killed. An al-Qaida \"strategy guide\" that US intelligence agencies intercepted in 2010 showed the group was thinking about using balloons or model airplanes to monitor drones, giving those targeted a chance to escape, the Post said. Source: UPI