Unconfirmed reports from Pakistani and U.S. intelligence sources indicate a CIA airstrike was carried out against a compound in Pakistan which contained Ayman al-Zawahiri, al Qaeda’s number two in command, and four other unnamed senior al Qaeda leaders. Eighteen people are believed to have been killed in the strike. According to Reuters, “A Pakistani intelligence official said four U.S. aircraft had intruded into Pakistani airspace and fired four missiles.” The Counterterrorism Blog quotes a source which indicate ten missiles were fired. The aircraft are believed to have been predator drones, presumably armed with Hellfire missiles. The strike is said to…