He formed Jama'at al-Tawhid wal-Jihad in the 1990s, and led it until his death in June 2006. Zarqawi took responsibility, on several audio and video recordings, for numerous acts of violence in Iraq including suicide bombings and hostage executions. Zarqawi opposed the presence of US and Western military forces in the Islamic world, as well as the West's support for the existence of Israel. In late 2004 he joined Al-Qaeda, and pledged allegiance to Osama bin Laden. After this al-Tawhid wal-Jihad became known as Al-Qaeda in Iraq (AQI), and al-Zarqawi was given the Al-Qaeda title, "Emir of Al Qaeda in the Country of Two Rivers".
In May 2004, a video appeared on an alleged al-Qaeda website showing a group of five men, their faces covered with keffiyeh or balaclavas, beheading American civilian Nicholas Berg, who had been abducted and taken hostage in Iraq weeks earlier. The CIA claimed that the speaker on the tape wielding the knife that killed Berg was al-Zarqawi. The video opens with the title "Abu Musab al-Zarqawi slaughters an American." The speaker states that the murder was in retaliation for U.S. abuses at the Abu Ghraib prison. Following the death of al-Zarqawi, CNN spoke with Nicholas's father and long-time war activist Michael Berg, who stated that al-Zarqawi's killing would lead to further vengeance and was not a cause for rejoicing.
In September 2005, he declared "all-out war" on Shia Islam in Iraq after the Iraqi government offensive on insurgents in the Sunni town of Tal Afar. He dispatched numerous suicide bombers throughout Iraq to attack American soldiers and areas with large concentrations of Shia militias. He is also responsible for the 2005 Amman bombings of three hotels in Amman, Jordan. Zarqawi died in a targeted killing on June 7th, 2006; while attending a meeting in an isolated safe-house approximately north of Baqubah. Two United States Air Force F-16 Fighting Falcon] jets dropped two 500-pound (230 kg) guided bombs on the safe-house.