Russia's intervention in Syria is the most remarkable military and political campaign of Putin's era, the first post-Soviet substantial military foray beyond the borders of the former USSR. For historical purposes, Russia's intervention in Syria, more than anything else, marks its return to the global arena as a player with whom other powers--led as they are by the United States--must contend, albeit reluctantly.
Clearly, the decision to dispatch a Russian military contingent to Syria was a very risky step in military, foreign policy, and domestic policy terms. The military intent whereby the operation would be limited solely to aerial bombardment and support of an ally fighting on the ground appears reasonable and moderate; however, one might recall that, in the early days in Vietnam, the Americans pursued a similar course, and look how things turned out. Internationally, Russia is plunging headfirst into the boiling cauldron of Middle East politics, complete with endless contradictory relations and links, and, by doing so, risks multiplying the ranks of its foes. Finally, the Russian public does not approve of any substantial costs (let alone in servicemen's lives) of something that most Russians view as an “Arab turf scuffle”. Therefore, domestic support of Russia’s military involvement in Syria, which relies solely on emotion-driven chauvinism and yearning for a great power status can only survive as long as the campaign does not turn into a burden or cause serious losses.
No doubt, strategically, Russia’s decision to intervene in Syria should be viewed in the context of a broad global game between Moscow and the United States, as a strong move designed to set the stage for righting the boat of Russia-US relations, heavily tilted by the events of 2014-2015, on a broad range of issues, including Ukraine. To a certain extent, these tactics have worked as the USA has been forced to urgently reinstate military contacts with Russia, which the Americans have made an ostentatious show of boycotting since early 2014.
The core problem of the Russian military operation in Syria is its presumed dual nature. On the one hand, the campaign's officially stated objective is to combat the extremist and barbaric Islamic State (IS) that arose in the flames of the Syrian and Iraqi civil wars, is threatening to change the map of the entire Middle East, and has evolved into an openly-run terrorist state never before seen in human history. On the other hand, falling just short of being goal number one of the Russian intervention, is the support to the regime of Syrian President Bashar Assad. If the regime’s military situation cannot be radically improved (which is unlikely), then at the very least its military and territorial positions could be consolidated to facilitate a peaceful settlement in Syria--while removing the issue of Assad’s ouster as a precondition.
The rationale is simple and obvious: if Assad’s regime remains and acts as a legitimate party to the process of intra-Syrian peaceful settlement, the regime would automatically become the strongest key party to such settlement (especially in the presence of direct Russian military support). Therefore, in addition to securing the survival of the Damascus regime, it would also guarantee a “controlling stake” in deciding the future of all of Syria.
It has become obvious that the Kremlin's decision to intervene in Syria militarily was largely prompted by plans for a Syrian “no fly zone” that Western nations have been discussing behind closed doors in recent months. Such a zone was intended to protect the forces of Syria's “moderate opposition” from the Syrian Government Army (Syrian Arab Army, a.k.a. SAA). It is perfectly clear that such a “no-fly zone,” one intended to replicate the 2011 Libya scenario, would actually have meant a transition to a large-scale air campaign directly waged by Western nations (along with Turkey and the Gulf Arab states) against Assad’s ground force. This would have dramatically undermined the latter’s already precarious military situation.
Any decision on a “no fly zone,” which the West had all but agreed upon by September, has been torpedoed by Russia’s resolute deployment under the banner of fighting the IS. The question is how long--and how efficiently--the Russians will be able to fly that banner.
While Russia's air campaign in Syria has been accompanied by a tsunami of PR and propaganda that is unprecedented for its Ministry of Defense, a fair amount of caution is advised in assessing the overall effectiveness of the Russian air strikes. In the first six days of the operation (between September 30 and October 5), the Latakia-based group comprising 30 strike aircraft (12 Su-24Ms, 12 Su-25s, and six Su-34s) of Russia’s Airspace Forces (ASF) flew approximately 120 attack missions hitting 51 targets.
For comparison's sake, between June 14, 2014 and September 29, 2015, as part of the Inherent Resolve operation against IS within Iraq and Syria, the US and allies flew 56,819 sorties (admittedly, that number includes support flights) and delivered 7,162 air strikes (of which 2,579 in Syria). It would be mistaken to suggest that they had any radical impact on the IS forces' activities, let alone achieved the Caliphate’s destruction. Notably, the Western coalition has almost exclusively relied on precision air munitions (whereas the Russian group also makes heavy use of old-fashioned gravity bombs); it possesses much more efficient reconnaissance, target selection, and targeting facilities (suffice it to mention the extensive use of relevant under-wing pods, which the Russian ASF has exactly zero of); and generally has much vaster and virtually non-stop 25-year experience of deployment and combat operations in the region, complete with well-oiled mechanisms for interaction and air force combat operations.
Therefore, the Russian air strikes have had (and likely will have) a limited and, probably, largely moral significance in terms of impact on ISIS forces proper. At the same time, Russian ASF actions could have much more substantial sub-strategic impact on the situation at the frontline of the SAA's fight against other rebel groups, whether "moderates" supported by the West or radical Islamists, such as Al-Nusra.
The Russian intervention in Syria occurred at a time when the situation of Assad’s forces somewhat stabilized. Notably, the Russians refrained from intervening in July and early August 2015, when the SAA suffered substantial blows at the hands of its opponents (first and foremost, radical Islamists). By September, Assad had managed to restore the frontline’s integrity, while the Islamist assault had lost its steam. This once again demonstrates that, in making its decision to intervene in Syria, Moscow gave more consideration to external factors (such as the threat of Western intervention) than to internal Syrian aspects.
By now, pro-Assad forces have managed to build up certain reserves, which include Iranian forces deployed in Syria and comprise extensive deliveries of Iranian and Russian weaponry. Apparently, in the near future (October), the SAA and its Shiite allies intend to mount an offensive operation with Russian air support.
A major problem for the pro-Assad forces has been created by large Islamist enclaves (mostly in Homs and Rastan) on territory under their control; the enclaves tie up a sizable proportion of SAA forces. The top priority for the Assad loyalists is to eliminate those enclaves. To the extent one can tell, a sizable share of Russian air strikes is currently de facto meant to assist an onslaught on those enclaves.
Should the enclaves be liquidated, Assad forces' subsequent objectives would be to completely sanitize the area around Aleppo, stabilize their positions in the south of Syria and, preferably, recapture the major communication hub of Palmyra from IS, driving the latter into the Syrian desert. If those objectives are achieved, the Assad regime's military and political position would significantly improve, and the regime’s survival would no longer be at stake.
However, the opposition forces (both moderates and Islamists) likewise are building up their potential for warfare. The US and allies have been supplying the “moderate” opposition with massive amounts of weaponry, and it looks like the Russian intervention in Syria has only put this process in higher gear. In December or January, the opposition forces of all hues could be expected to undertake a large-scale offensive along key directions. Rebuffing the offensive would be a crucial task for both SAA and the Russian air group. The very existence of the Russian group could be a serious factor delaying the opposition's offensive, for instance until January, which would benefit the government forces. In Syria, the period from February to April is taken up by the Khamsin (sandstorm) season; it largely rules out active operations of the parties.
Therefore, should Damascus and Moscow see their best-case scenario pan out, a situation might evolve by the spring of 2016 that would lay ground for negotiations on Syria’s potential future with the participation of Assad’s regime, the "moderate" opposition, both parties' sponsors and, potentially, a moderate section of Islamists (other than IS or Nusra).
Here, the fundamental remaining issue would be the very existence of Syria within its present-day borders, given that the Kurdish regions have effectively undergone self-determination. In addition, it appears that a complete military victory over ISIS remains impossible in the foreseeable future, and the Caliphate will keep large areas of Syria and Iraq under its control.