ISIS was part of Al Qaeda. They are among Syrian Rebels that funded and armed by US, British, and Israel intelligence. Snowden said that. Hillary Clinton also said in front of Congressmen: "We've created Al Qaeda".
After getting Stronger, ISIS is not interested in toppling Assad only. But also trying to get the whole Syria and Iraq, and of course eventually the world as his "Islamic Caliphate" with him as the first Caliph.
There are some photos of ISIS leader, Al Baghdadi with John McCain in Syria. McCain there to give money and weapons to the Syrian Rebels. ISIS get sophisticated weapons from US so the Syrian, Iraq, and Kurdish soldiers are no match for them is not supported by jet fighters.
ISIS are killing Shia, Muslim scholars, even the Al Qaeda fighters. Even Al Qaeda said ISIS are evil.
ABU BAKAR AL BAGHDADI MET JOHN MCCAIN IN IDLIB SYRIA MAY 27TH 2013. AT THAT TIME AL BAGHDADI WAS A MODERATE MUSLIM. AL BAGHDADI GET SOPHISTICATED WEAPONS, MONEY, AND TRAINING FROM CIA IN JORDAN
it does not mean that hr was the with FSA (as it was ISIS) but have encountered this day of May 27, 2014.a year ago, when al-Baghdadi was not considered yet as a religious extremist, he had received in Idlib the Senator John McCain.