ISIS (Islamic State of Iraq and Syria) is an extremist group formed from al-Qaeda offshoots in Iraq and Syria. Since its formation in 2013, ISIS has worked to sustain a self-declared caliphate in eastern Syria and western Iraq. Ultimately, ISIS seeks to unite the world under a single caliphate, and to that end the group has begun to establish satellite operations in nine countries. Initially, ISIS gained support within Iraq as a Sunni insurgency group fighting what some Sunnis viewed as a partisan Shiite-led Iraqi government. The group has since garnered additional momentum as a result of the Syrian civil war, and has recruited up to 33,000 fighters from around the world. Thousands of foreign ISIS fighters are estimated to have been killed in battle, while some have returned—or are reportedly planning to return—to their home countries.
