It's crazy there are still people here who don't realize that ISIS was created because of US involvement. Great book with link below on the topic of America's actions in the middle east that talks about everything starting from Carter in the late 70s to time of publishing in 2016. Highly suggest reading.
Under the Obama administration the CIA was funneling billions of dollars worth of military equipment -- ranging from small arms and ammo, to vehicles and even anti-tank missiles -- into the hands of Syrian militant groups[1][2].
These groups specifically include ISIS.
It's hard to think that the Syrian civil war would have been so bloody or lasted as long as it did without USA involvement.
Syria had a civil war before significant US involvement, but between being bordered by a completely destabilized Iraq, and the US campaign against Assad means that US involvement made the situation so much worse.