It emerged from the remnants of al Qaeda in Iraq (AQI), a local offshoot of al Qaeda founded by Abu Musab al Zarqawi in 2004. It faded into obscurity for several years after the surge of U.S. troops to Iraq in 2007. But it began to reemerge in 2011.
The principle cause of the war was that those states harbored and supported the actions of pirates against American shipping vessels in the Mediterranean Sea.