Thank you, Mr. Cotler, for your question. As usual your question is very simple but yet very complicated.
Let's backtrack a little about ISIS and who they are. You need to understand that ISIS is a branch of al-Qaeda. The leader of ISIS is Abu Bakr al-Baghdadi. The leader of al-Qaeda, Ayman al-Zawahiri, wanted ISIS to focus on their territory in Iraq. They wanted Jabhat al-Nusra, which is another branch of al-Qaeda, to focus on Syria. That's when Abu Bakr al-Baghdadi disagreed with Ayman al-Zawahiri and separated. Now ISIS has become separate from al-Qaeda. ISIS is the child of al-Qaeda but they disagreed on which territory belonged to you and which territory belonged to me.
ISIS was born, and we can see the monster right now.
With regard to the situation in Syria the world did too little too late. Now the problem is literally way bigger than us. We have two devils to deal with and we have to choose between them: the Assad regime or the two extremist groups.
The only way we can have a sense of fixing, that we can cooperate with local groups, is that we have the sense from them that maybe they are moderate enough or they have a sense of democracy or they will be able to ensure protection of minorities. However, history teaches us, especially American history, that this is really a tricky game because America supported Osama bin Laden during the mujahedeen war in Afghanistan and turned against him. It supported Saddam Hussein during the Iranian war, the first Arab Gulf war, and turned against him. It supported the rebels in Libya who killed their American ambassador three months later.
The truth and the reality are we have to choose the only solution, that we work with local groups that we trust. I will not name them because I simply don't trust any of them. We have to work with local groups to be able to get out of the problem in Syria.
That's my simple answer. I hope this answer helps you.