S-400, Explained – With air superiority over the skies of Ukraine still challenged, much attention has been given recently to Ukrainian air defense. Though the Ukrainian military has operated an S-300 surface-to-air missile (SAM) system, these platforms took big hits early in the war, leading to the transfer of additional S-300 assets from Slovakia to Ukraine this spring.
Given the challenges Ukrainian air defenses have faced, there has been additional chatter from the United States over whether Turkey might consider sending its recently purchased S-400 SAM battalions to Ukraine. Because Turkey was recently kicked out of NATO’s F-35 Lightning II program over its purchase of the S-400 system from Russia, such a transfer would not only significantly boost Ukrainian air defenses, but also potentially allow Turkey to reenter the F-35 program.
For a variety of reasons (namely that Turkey feels it needs the S-400 in its geopolitical goals vis-à-vis Greece and the country seeks not to further upset Moscow) that outcome seems unlikely. Nonetheless, the hypothetical raises interest in the capabilities of the S-400 system, a system increasingly being sold by Russia on global markets.
What Is the S-400?
The S-400 is a fourth-generation mobile SAM system and the upgraded version of the S-300. Development began in 1993, with the system first entering service in Russia in 2007. The S-400 is capable of engaging aircraft, UAVs, and cruise missiles. Many consider it similar to the US Patriot SAM system, although unlike the Patriot system, the S-400 doesn’t currently employ hit-to-kill ballistic missile defense technology. The S-400’s range is roughly 250-400 kilometers (although it is unclear whether or not its radar capabilities would allow one of its missiles to actually reach 400 kilometers) and its missiles carry a 143-kilogram high explosive fragmentation warhead.
Though the S-400 primarily uses the 48N6 missile series to hit aerial targets up to 250 kilometers away or intercept ballistic missiles across a 60-kilometer radius, the system also employs the 40N6, a long-range missile designed to extend air defense capabilities out to the aforementioned 400 kilometers. In addition to these two missiles, Russia is currently testing the 77N6, a missile using hit-to-kill technology and designed specifically to counter ballistic missile warheads. If the development of the 77N6 is successful, this would put the S-400 system more on par with the US Patriot system.
Since entering service, the S-400 has seen a number of high-profile deployments, such as in Russia’s highly militarized European enclave of Kaliningrad, the Crimean Peninsula and in Tartus, Syria, where it protects Russian and Syrian military assets.
Exports of the S-400 are growing. In 2015, China contracted with Russia to purchase six battalions of the system. The following year, India purchased five. Most recently (and controversially), Turkey received shipments of the system in 2019.
The spread of the S-400 to countries such an India has been controversial within some US policy circles. Yet others have argued that the S-400 provides India with a more affordable system that can be used to counter China in south Asia.
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What is for certain is that the spread of the S-400 system will remain controversial: for the export revenues it brings Russia, the A2/AD capabilities it provides China, and the interoperability issues it presents NATO allies such as Turkey. Though Ukraine won’t be receiving this system anytime soon, the specter of its further spread raises valuable questions for both regional and global balances of power.
Alex Betley is a recent graduate of the Tufts University Fletcher School of Law and Diplomacy where he was an International Security Studies Civil Resistance Fellow and Senior Editor with the Fletcher Security Review. Suparna Malia contributed research to this article.