I should add to this post of mine:
Russia also is operating
SU-30s in Syria, which are extremely modern fighters, equivalent to an F/A-18E/F Super Hornet or F-15E Strike Eagle. They'd give everything in the sky except an F-22 a run for its money.
Also, the
SU-34 is deployed in the region, it is mostly a strike-fighter, designed for Air-to-Ground and Air-to-Sea operations. It's more modern than the SU-30, but because of its design is not as capable in air-to-air operations.
A few weeks ago the US moved a few jets from a
squadron of F-15C's from England to Turkey. This is interesting because this squadron trains
exclusively in air-to-air combat, their jets are never, ever purposed for air-to-ground operations.
The US also has F-22s operating out of Al Dhafra in the UAE. It's fairly tragic the F-22 program was cut so short by politicians, as it's so vastly superior to anything else in the sky. In air-to-air operations, it would most likely hand the F-35 its lunch.
A potential scenario here is Russia deploying Anti-Air defenses in Syria. This would give Russia the capability to close off Syrian airspace to pretty much anything other than F-22s and B-1 Stealth bombers, and even then it would be problematic.