The earth is round. There was never a way Russia's radars 200 km away could detect relief-hugging missiles
Could Russia have in some way thwarted Trump's April 6th cruise missile strike against the Syrian military but chose not to? According to Russian military analysts the answer is no. Bringing down those missiles was never a possibility for the Russian air defense systems in Syria because they are stationed too far away and are not primarily designed to counter cruise missiles.
In other words, the US planned its strike mission around the Russian capabilities and chose precisely the mode of attack that could circumvent Russia's otherwise potent S-400 and S-300 anti-air systems.
The Americans launched the strike 1,100 km off Syria's coast. This is too far for even the most powerful Russian radar to detect. The Tomahawk missiles used are old and slow but they are also low altitude. Flying at no more than 50-60 metres off the ground there is not even a theoretical way they can be detected by radar that is more than 24-26 km away. The Russian anti-air systems however were in Latakia and Tartus some 200 km away. From such a distance they are still effective against high-flying fighter jets and ballistic missiles but not against relief-hugging Tomahawks.
A Washington Think-Tank helpfully gathered information in the Russian press:
These systems are not principally designed to counter low-flying subsonic Tomahawks; their capacity to attempt this is limited to approximately 30–40 km. Colonel (retired) Mikhail Khodarenok, a defense correspondent for Gazeta.ru and an air defense specialist, notes the Al-Shayrat airbase is located around 200 km from Latakia, which he suggests lies at the outer limit of the S-400 range: to strike a target at this range requires it to be flying at an altitude of 8–9 km. If it flies lower, the S-400’s multifunctional radar cannot see the cruise missile due to the curvature of the Earth’s surface.
Similarly, the S-300V4 at Tartus has a range of around 100 km and requires a target altitude of 6–7 km. According to Air Force Colonel General (retired) Igor Maltsev, the former chief of the Main Staff in the Air Defense Troops, since Tomahawks fly at 50–60 meters above the ground, the outer effective range for the S-300V4 system would only be around 24–26 km in cross country terrain. Maltsev concluded that the S-400 and S-300V4 located in Latakia and Tartus did not have even a theoretical chance to counter the US cruise missile strike.
Moreover, to protect against a similar strike in the future, Maltsev believes Al-Shayrat would need four to five S-400 battalions, alongside a radar reconnaissance system to provide depth of detection against cruise missiles, in addition to an air regiment of Su-30SM or Su-35 fighters (Gazeta.ru, April 7).