On July 25th 2017 the deal between Moscow and Ankara for the sale of S-400 surface to air missile systems to Turkey was finalised. Turkish President Recep Tayyip Erdogan announced: "Russia and we took necessary steps, signatures have been put, we hope to see S-400 in our country and will do joint production of them." Russia will not only sell the S-400 to Turkey, but will also provide key technologies to Turkey's defence industry through joint production of the missile system.
The S-400 is critical to the defence not only of Russia's mainland, but also to its military forces in Syria to which it provides cover from air attacks. Technologies derived from the system are also deployed on Russia's naval vessels. Other than Russia, the S-400 is also deployed extensively in the defence of several Russian military allies such as China and Algeria. Russia is considered a world leader in surface to air missile capabilities, the development of which it has long prioritised as a countermeasure and security guarantee against air attacks by the United States and its Western allies. Of these SAM systems the S-400 is among the most advanced, and in a long range anti aircraft roll is unmatched worldwide. With its unparalleled range and anti-stealth capabilities it is a key means of denying fifth generation Western aircraft access to zones of conflict from the Middle East and North Africa to Eastern Europe, Central Asia and East Asia where it is currently deployed. Should the technologies inherent in the system be compromised however, this would be a critical blow to Russia's defence.
In the past Western allies which have gained access to Russian SAM technology have shared detailed information with the Western bloc and with one another to search for weaknesses to overcome such missile systems. One key example was the S-125 sold to Egypt in the early 1970s which proved highly effective against Israeli forces in the 1973 Yom Kippur War. These systems were, along with MiG-23 fighters, subsequently turned over to American and Israeli analysts as a result of Egyptian President's Sadat's pivot westwards. Israel in particular benefitted from this information, which it used to quickly and effectively neutralise Syria's S-125 missiles and MiG fighters in 1982 during Operation Mole Cricket with minimal losses and thus gain near unrestricted access to Syrian territory. Another key example was the S-300 sold to Cyprus, which ended up under the Greek military. Greece allowed other NATO states and Israel to train with their S-300 systems to find and exploit weaknesses, as these states all expected to face S-300 systems in potential conflicts with the USSR or its client states. The aim again was to render the S-300 ineffective as had been done with the S-125.
Turkey remains a NATO member, and one whose alliances have been prone to undergoing sudden shifts over the past seven years. Once a close partner to the Syrian government, Turkey quickly became one of the anti-government insurgency's strongest supporters in 2011. In 2016 it again pivoted and announced potential cooperation with the Syrian government. Turkey also went from being a close Russian partner to shooting down a Russian strike fighter in 2015. It was as a direct result of this that the S-400 was first deployed to Syria - as a deterrent to prevent further Turkish or NATO air attacks on Russian forces. In 2016 Turkey again pivoted and President Erdogan visited Russia to amend relations. What this record shows however is that Turkey is hardly a consistent party when it comes to its foreign policy alignment, but rather an opportunist party.
Turkey's relations with Russia are currently positive, but after acquisition of the S-400 precedents suggest that this could quickly and unexpectedly change. While Russian state media has hailed the sale of the S-400 to Turkey as a victory over Western manufacturers, Russia more than any party has a great deal to lose. At only $400 million per division sales of the S-400 will hardly be a major contract for Russian defence industries considering that they will put Russia and its allies at risk of having one of their most potent and critical defence systems compromised. If Turkey and NATO states were to analyse and learn to compromise weaknesses in the S-400 it would be a major asset to the United States and its allies affecting power balances in Europe, the Middle East and even the South and East China Seas where S-400 missile coverage serves as a critical asset to Chinese defences. Knowledge of how to counter the S-400 would therefore be invaluable to the U.S. military worldwide, and something the United States could compensate Turkey generously for providing.
Should the S-400 be compromised there are no more modern systems with comparable range confirmed to be in development which can replace it in the near future. While the compromising of the S-125 and S-300 could be compensated by deployment of the S-200 and more advanced variants of the S-300 respectively, there is no more advanced anti aircraft systems set to enter service anytime soon. The S-500 currently under development is to replace the S-300VM as an anti missile and anti satellite system, and is not suited to the role of an anti-aircraft system as is the S-400. While the S-400 export variants will inevitably lack key classified technologies and therefore not be identical to the S-400 systems operated by Russia's own military, based on historical precedents there may well far more to be lost from a sale to Turkey that there is to be gained.