You know, a few years ago everyone was lobbing spitballs at us for our idea of "preemptive war" and being the global police force. Now they want us to go help them out when it is not, in any way, in our interest to do so. Funny stuff.
Let me give you the options. ISIS/ISIL are currently active in the Levant region and Iraq, a region destabilized by decades of constant war and the Arab Spring. They are vultures, feeding on the carcass of states. While they may, someday, become an organized state, that is far off and will never be recognized. They will be subjected to the harshest economic sanctions the world can throw at them, enough to make interwar Germany look like Dubai. They become a Sunni state, war continues in the Middle East, but they come up against brick walls on all sides. Iran is the global capitol of Shia Islam, and ISIS/ISIL are Sunni. I'm sure that Iran, who is reasonably militarily powerful, would love to see an expanding Sunni power on their doorstep. Israel wouldn't be too happy either. Turkey has been having difficulties with radicals and they don't want anything to make that worse. Russia doesn't want anything to risk its business interests, China is the same plus they don't want an expanding Muslim power that could rile up the Chinese Muslims.
The point is, ISIS/ISIL are quixotic. They will never be able to establish their Caliphate, because every single power, particularly Iran, who is largely responsible for much of the Muslim terrorism that has harmed the West, wants them to fail. If they do anything but kill a bunch of people, most likely that will be to give Iran and the West the detante they've been pursuing but without the political excuse to go public with. Worst case scenario: Taliban situation in the region. Big whoop. Best case? They'll pick a fight with anyone and get crushed.
They can't use them because they are gone. They've either been scuttled (blown to smithereens) or removed. No air force would abandon an airfield with a functional fleet of aircraft, and all signs are that the Syrians made good. This is fearmongering, and inept fearmongering at that.