It was fully foreseeable as far back as 2009, and what Russia perceives is that it’s now happening. The answer to the “why now” question about Russia’s intervention in Syria is: “Because Turkey is using the coalition with the U.S. to make her move on Syria.”
Don’t get confused: Turkey has no intention of deploying vast armies to Syria to wage a conventional war of conquest. But that’s why Turkey needs to cultivate one faction in Syria and weaken another. ISIS has the potential to be a convenience for Turkey in Syria, which is why there have been so many reports of Turkey quietly supporting ISIS there. Turkey just has no intention of letting ISIS have the upper hand.
Turkey also doesn’t intend to destroy the Kurds. They make a fine buffer: a guarantee of strategic depth on Turkey’s border. But Turkey needs to keep the Kurds cowed and quiet.
Russia
Russia, meanwhile, wants to avert a worst-case scenario in which Turkey does gain effective control over Syria – however Turkey might manage it (e.g., through factions inside Syria). Russia’s concerns here are geographical as well as political. These concerns have been held in a tense stasis since Harry Truman proclaimed the Truman Doctrine, and Soviet Russia understood that she would be blocked in military-strategic terms at the entrance to the Mediterranean Sea – but the United States would administer a status quo in which Russia would have access for non-military purposes.
Russia has never been satisfied with an outside power exerting ultimate control over the regime of access between the Black Sea and the Mediterranean. But for nearly 70 years, she has not thought it worth fighting over, because America’s power has ensured that the regime of access doesn’t change. Russia has been able to count on it.
She no longer can. Obama’s America is behaving like a geriatric in an advanced stage of dementia, squandering our legacy on the nutty projects of radicals. That’s how strategists in Moscow see what we’re doing by joining forces with Turkey in Syria, and then standing by as Turkey ignores American intentions, and simply pursues her own.
Russia also sought throughout the post-World War II period to guarantee that she had friendly points in the Mediterranean, outside the Black Sea, to leapfrog to. Yugoslavia was one of these during the Cold War. Syria was another.
Both patches of territory are of special importance, not only because they’re outside the Hellespont, but because they flank Turkey. Russia’s view of the need to flank Turkey goes back centuries prior to the NATO alliance – perhaps even to the 14th century, when Slavic Christians were fighting Ottoman invaders for Belgrade, in what is now Serbia. The consolidation of the Ottoman Empire in the next century, with its seat in Istanbul, was a strategic blow to Russia, killing off the remnants of the old Orthodox Byzantine Empire, and turning Russia’s access point to the Mediterranean into the Ottomans’ bridge into Europe.
If you were Russia, you’d be perpetually nervous too about the disposition of the territory around the Black Sea. Moscow can’t afford to let Turkey – especially a resurgently Islamist Turkey – consolidate a swath of territory that would leave Russia unable to exert power or influence across this major access point.
And in 2015, Turkey is more likely to begin trying to do that than at any time since the Ottoman Empire was dismantled in the settlement after World War I.