President Barack Obama presses ahead with his campaign to diminish and eventually defeat Islamic State group extremists in Iraq and Syria, but the list of radical Islamic elements the United States and many of its coalition allies are fighting does not stop there. Led by Iraqi militant Abu Bakr al-Baghdadi, it stormed into the Syrian civil war in 2012, seeking to oust President Bashar Assad and was initially welcomed by other rebels for its experienced fighters. Al-Qaida's central command ejected it from the network for its clashes with other rebels, but it has thrived, backed by foreign fighters from Chechnya, Europe, the U.S.