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In November 2015, a Turkish F-16 shot down a Russian Air Force Su-24 Fencer bomber for violating Turkish airspace on the border with Syria. In response, Russia pointedly deployed its most capable operational air defence system, the S-400 Triumf, to Latakia air base. Analysis and reactions at the time focussed on the formidable theoretical capabilities of the S-400 and its huge advertised 400 km range which would place a large portion of Syria, the eastern Mediterranean and southern Turkey inside its missile engagement zone. Russia also bases four of its most modern operational air superiority fighter, the Sukhoi Su-35S, in Syria. The Su-35 is the next step in the evolution of the famous Su-27/30 Flanker family of 1980s vintage, and can theoretically pose a serious danger to all coalition aircraft with the exception of the scarce and extremely expensive US Air Force F-22 Raptor stealth fighter. Russia has invested heavily in setting itself up in the non-Western aligned world as the defender of the regime of Syrian President Bashar Al-Assad against US-led regime change efforts and has deployed its most potent air defence assets to provide deterrence against any such strategy.
The S-400 surface to air missile (SAM) system is one of Russia’s most important assets in Syria, as well as in Eastern Europe where the system’s presence in the Russian enclave of Kaliningrad gives the Kremlin powerful airspace denial options over the Baltic States and much of Poland. The S-400 system consists of wheeled vehicles including long-range surveillance radars, tracking and engagement radars, missile transportation and launch vehicles, and a command and control node. The radars include variants for ballistic missile defence and the capability to more easily detect stealth aircraft, and are frequency-agile and hard to jam. The system uses a family of large missiles for short-, medium- and long-range engagements and is advertised as being extremely capable against aircraft, cruise missile and ballistic missile targets. In practice, the system’s engagement range is far shorter than the advertised 400 km since the very long-range 40N6 missile is still in testing and non-operational, limiting the system to engagements inside 250 km. However, the S-400 is rightly considered one of the most capable SAM systems in service anywhere in the world and is one of the most feared threats that a Western fighter pilot could encounter in combat today. Even if attacked, the S-400 battery at Latakia is protected by the Pantsir S-1 point defence system which combines radar guided rapid-firing cannons and short range missiles to intercept incoming threats at short range including precision guided munitions. On paper, therefore, the S-400 gives Russia the ability to threaten or even halt US-led coalition air operations over most of Syria. However, this deployment of capabilities has created problems for the Kremlin.
The largely ineffectual strike by US Navy ships using 60 BGM-109 Tomahawk land attack cruise missiles (TLAMs) against the Syrian Air Force base at Shayrat – in response to a chemical weapons attack on Khan Sheikhoun two days previously – was the first major illustration of Russia’s difficulties surrounding its air defence capabilities in Syria. In the days following the US strike, many questioned why Russia's much vaunted S-400 had not been used to intercept the US TLAMs during their subsonic flight towards Shayrat, despite Russia having been given sufficient advanced warning by the US military to evacuate any personnel or equipment that they had on the base. TLAMs are a relatively old cruise missile design and lack radar-cross section reduction features or sophisticated jinking or manoeuvring capabilities to avoid interception. However, for Russia the strike presented a real challenge.
The S-400 battery at Latakia can fire between 36 and 48 missiles (depending on whether medium or heavy launcher vehicles are used) before needing to reload. Standard Russian SAM doctrine is to fire two interceptor missiles at each target to increase the probability of a hit. Therefore, had Russia attempted to engage the TLAMs with the S-400 system, it would not have been able to destroy more than about half of the incoming missiles even assuming all of the SAMs loaded and ready were fired and all hit their intended single targets – an unlikely outcome. This would have seriously depleted Russia’s available stocks of defensive missiles in Syria without preventing even a limited US strike from getting to its target using relatively old cruise missile technology – hardly an ideal outcome. If – as is much more likely – some of the S-400 interceptor missiles had missed or malfunctioned (the system is still maturing and is not combat proven), then Russia’s key asset would have been shown to be far less effective even against fairly easy targets than the hype around its deployments in Syria and Kaliningrad assumed. This is probably the key reason why the S-400 system was not used to defend Shayrat – a major military hub for Russia’s key ally.
The shooting down of a Syrian Air Force Su-22 bomber by a US Navy F/A-18E Super Hornet on 18 June 2017 means – in effect – that the US is now calling the Russian air defence bluff in a much more open way. Following the Turkish Su-24 shootdown and the US strike on Shayrat, Russia made threats and implied that it could target coalition aircraft to protect both its own assets and those of its Syrian ally. Similarly, in June 2017 Russia threatened to track, ‘escort’ and treat coalition aircraft west of the Euphrates as targets using the S-400 and its own Su-35s. However, while each individual coalition sortie within range of the system using non-stealth aircraft would indeed be at very high risk if actually launched upon by the S-400, the Kremlin has compelling reasons to avoid doing so at all costs. The escalation risks of firing on a coalition aircraft are huge and obvious to all concerned – the same reason why strenuous deconfliction efforts are undertaken by the coalition to avoid clashes with Russian aircraft. Moreover, if the S-400 were used, tit-for-tat escalation would very likely occur, and the Shayrat example shows how attacks with TLAMs and other standoff weapons could quickly overwhelm the S-400 and even its Pantsir point defences at Latakia. Likewise Russia’s Su-35s and other Flanker derivatives in Syria are all capable of meeting coalition fighters other than the F-22 on equal terms one on one, but they are heavily outnumbered and would be very unlikely to come off better from a flashpoint engagement.
Russia relies on bold deployments of its military forces to intimidate other powers into backing down in Eastern Europe and the Middle East and has achieved great success in Ukraine, Georgia and initially in Syria. However, with a US administration which is clearly more comfortable with taking military risks in Syria in areas defended by Russian forces, the Kremlin’s bluff has been called. Non-Western states which traditionally look to Russia have seen Turkey shoot down a Russian jet, with no lasting consequences, the US strike Shayrat air base with impunity and most recently shoot down a Syrian Air Force Su-22 (and two armed drones) within Russia’s vaunted air defence coverage again without notable consequences beyond angry rhetoric. The risks to Russia’s international reputation will be clear to the Kremlin, but Putin’s challenge remains the fact that in even a limited military clash in Syria, it is very unlikely to come out on top against a US administration that is clearly comfortable with running significant risks and is well aware of its military advantages.
Research Fellow for Airpower at RUSI