The US Navy's ability to hit Syria's Al-Shayrat Air Base with a large number of Raytheon RGM-109 Tomahawk Land Attack Missiles (TLAMs) on 7 April raised questions about the capabilities of Russia's air defence systems, specifically its current frontline long-range system: the Almaz-Antey S-400 Triumf.
Russia deployed a S-400 battery to its air base in Syria's Latakia province in November 2015 after one of its Su-24 strike aircraft was shot down by a Turkish F-16 fighter close to the border.
The Russian Ministry of Defence announced in October 2016 that it had also deployed a S-300 system to the Syrian naval base at Tartus. This followed a US report citing US officials as saying an SA-23 'Gladiator' system - an apparent reference to a S-300V4 - had been deployed to Tartus.
Despite this bolstering of air defences in western Syria, 59 Tomahawks launched from two US Navy destroyers in the Mediterranean managed to get through to Al-Shayrat on 7 April, according to the US Department of Defense.
This prompted much criticism in numerous Russian publications and online forums about the apparent failure of the S-400 and S-300 systems to intercept the cruise missiles.
Both Western and Russian military analysts pointed out that the TLAMs could have flown low and close to the Lebanese border to ensure they were below the engagement envelope of the S-400, located some 80 km to the north, due to the Earth's curvature.
That flight path would have taken them through the engagement envelope of an S-300 in Tartus, but the deployment of this system has never been independently confirmed by satellite imagery.
If there is a S-300 near Tartus it could have been avoided by flying the Tomahawks across Lebanon, at which point only sophisticated short-range air defence systems deployed at Al-Shayrat would have been able to significantly mitigate the scale of the attack.
Want to read more? For analysis on this article and access to all our insight content, please enquire about our subscription options ihs.com/contact