American forces have captured a key operative in the organization of Iraq's al Qaeda leader Abu Musab al-Zarqawi, the top U.S. general said on Tuesday. Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, told the PBS program "The NewsHour with Jim Lehrer" that Monday's capture of Abu Abd Al-Aziz, whom he called Zarqawi's "main leader in Baghdad," was "going to hurt that operation of Zarqawi's pretty significantly." Myers said Al-Aziz was picked up "on the battlefield," but provided no other details.A defense official, speaking on condition of anonymity, added, "When you look at the picture of the Zarqawi network of the different elements that are known to exist, he's the second-in-command of the Baghdad element and has the reputation of being the 'emir of Baghdad' for Zarqawi." The official said American forces were involved in the operation that snared Al-Aziz, but was unable to say whether Iraqi government forces played a role. Al Qaeda Organization for Holy War in Iraq, led by the Jordanian-born Zarqawi, has carried out some of the deadliest attacks against U.S. forces, the Iraqi government and Shi'ite Muslims in Iraq as part of a tenacious insurgency.