Normally, Isis doesn't. These are the gold they stole from Assad. Isis is a band of thieves and killers which got planted in the Middle East by the US. That's the only thing you should be seeing in this article. Don't get drowned in the details.
Assad didn't cooperate with Israel, USA didn't like it. It is as simple as this.
A bit oversimplified but essentially true.
I just hope the Kurds don't end up taking it in the ass (again) out of the deal.
Also, fuck Erdogan.