Jihadism grew rapidly in Iraq following the 2003 U.S. invasion of the country. In 2004, one of the largest jihadist groups — Jamaat al-Tawhid and Jihad, led by Abu Musab al-Zarqawi — became an al Qaeda franchise group and renamed itself al Qaeda in the Land of the Two Rivers. It was also commonly called al Qaeda in Iraq.
In 2006, the group formed the nucleus of a coalition of jihadist groups called the Islamic State of Iraq. The group remained an al Qaeda franchise and was placed under an Iraqi leader.
The Anbar Awakening in 2006-2007, coupled with the 2007 surge of U.S. troops in Iraq, severely damaged the organization, as did the U.S. operation that resulted in the deaths of the group's top two leaders in April 2010. However, following the withdrawal of U.S. troops from Iraq, the group was able to recover, becoming one of the largest jihadist groups in the world.
The civil war in Syria has proved to be a boon for the group. Initially, it provided support to Syrian jihadist groups, but eventually it became directly involved in the fighting and is now perhaps the strongest single jihadist group operating in Syria. Its operations in Syria have caused it to change its name to the Islamic State in Iraq and the Levant, also known as ISIL or ISIS.
ISIS has attempted to subsume other Syrian jihadist groups, including the Syrian al Qaeda franchise group Jabhat al-Nusra. This led to a dispute that resulted in the group breaking from al Qaeda and fighting against Jabhat al-Nusra. ISIS is also fighting many other Syrian rebel groups.
In addition to its activities in Syria, ISIS continues to conduct terrorist attacks in Iraq and has a cadre of sophisticated terrorist operatives. The recent taking of Mosul, Iraq's second largest city demonstrated the group's robust and growing insurgent capability. They will use both their terrorist and insurgent capabilities in their quest to create an Islamic state.