here’s an alternative theory: Putin is attempting to control a much larger slice of the oil and natural gas pie so that, ultimately, he can put an end to petrodollar hegemony which would leave the west devastated and him as master of the universe.
I’d make a more realistic one. Let’s say that Iran, Syria and Russia get ISIS on the run, and they finally leave Syria. Where exactly will they go? Iraq or Saudi Arabia. In either case, they are dumping ISIS back onto the US and it’ll trigger some 50,000 men deployment back into either....by Feb of 2016. ISIS will be the US problem then....completely.