Evolving Air Defence in South Asia: The Role of the S-400 and Prospects for S-500 Joint Production in India’s Strategic Doctrine

As Pakistan launched airstrikes on Indian territory along the Line of Control (LoC) and the International Border in response to Operation Sindoor, much hope resided in the performance of the air defence systems to thwart those incoming attacks. Suffice it to say that India’s air defence systems delivered. This conflict has brought one of the most successful surface-to-air missile defence systems out in the mainstream, the S-400. Against the backdrop of this performance, Russia has proposed to India for the joint production of the S-500,  the next upgrade of this missile defence system. 

This analysis addresses the functioning and utility of air-defence systems in a country’s defence infrastructure and a detailed account of the S-400 long-range surface-to-air missile defence system as well as the prospects of a joint -production of the S-500. 

History of the S-400 air-defence system

Heightened conflicts and tensions often provide the perfect breeding ground for defence innovation. The S-400 missile defence system, for example, was born out of Cold War tensions. 

Its genesis can be traced back to the late 1980s within the Soviet Union, a period marked by significant shifts in the global political and military landscape. The system, developed by the Almaz Central Design Bureau, was initially conceived as a necessary upgrade and replacement for the Soviet Union's aging S-200 Angara/Vega/Dubna series of surface-to-air missile systems. It is crucial also to acknowledge the geopolitical situation of the time. The 1980s saw a marked shift in the engagement between the two superpowers - the US and the USSR - as the fissures between them deepened further. This incentivized the Soviet Union to invest in innovations in air defence systems to safeguard its security against the military threats posed by the Western bloc. 

This gave rise to the S-400, a comprehensive multi-layer surface-to-air defence system for the Soviet Union. The aim was not only to counter the threats posed by the traditional missiles but also to consider emerging technologies, stealth and cruise missiles, and ballistic missile systems. Interestingly, the initial proposal for the system faced rejection due to concerns over its high cost and perceived inability to address the growing threat posed by cruise missiles adequately. However, the program was subsequently revived under the codename "Triumf," signifying a renewed commitment to developing this critical defence capability. On August 22, 1991, the Soviet Union officially approved the programme. 

This initial rejection, followed by the program's revival, suggests the dynamic nature of military technology development, where evolving threats and technological feasibility continuously shape strategic priorities. Following the end of the Cold War and the dissolution of the Soviet Union, the Russian Air Force publicly announced the existence of the S-400 system in January 1993.

Figure 1: Timeline of the development of S-400 surface-to-air missile defence system

The system was scheduled to be integrated into the Russian defence infrastructure by 2001. However, subsequent testing and development were needed to make the system, as it was evident that it was not ready for operational deployment by then. Finally, on April 28, 2007, the Russian government officially approved the S-400 system for service.

The S-400 represents the fourth generation of Russian long-range surface-to-air missile systems, significantly evolving from its predecessors, the S-200 and S-300 families. Compared to the S-300, the S-400 incorporates several key technical advancements. These include upgraded radar systems boasting an enhanced detection range of up to 600 kilometers and the capability to simultaneously track up to 300 targets and engage up to 36 threats. The system achieves this by integrating multiple sophisticated radar systems, such as the 92N2E Grave Stone tracking radar, the 96L6 Cheese Board acquisition radar, and the 91N6E Big Bird acquisition and battle management radar. A notable feature of the S-400 is its ability to fire a wider array of missiles, each designed for different ranges and target types. These include the short-range, the medium-range, the long-range series, and the ultra-long-range missiles. The S-400 also exhibits improved mobility, with rapid deployment times of just five minutes while on the move and a mere 35 seconds from a standby state. Furthermore, the system features enhanced resistance to electronic warfare and incorporates counter-stealth capabilities, including advanced radars like the Nebo-M system that operate on different frequency bands. While domestic and export variants are believed to exist, detailed information regarding specific export versions remains limited.

India’s acquisition of the S-400 system

On the sidelines of the BRICS Summit 2015, India and Russia came together to sign the Inter-Governmental agreement for the supply of five S-400 systems. India's Defence Acquisition Council (DAC) granted its approval for the procurement on July 1, 2018. This was followed by the Cabinet Committee on Security (CCS), headed by Prime Minister Narendra Modi, which provided the final clearance on September 26, 2018.  Finally, the formal contract, valued at approximately USD 5 billion for five squadrons, was signed on October 5th, 2018. 

The acquisition of the S-400 defence systems was not only crucial because of the viability of this system in enhancing India’s defence capability but also because of India’s resistance to intense pressure from the US against signing this deal. In 2017, the United States threatened India with sanctions under its Countering America’s Adversaries through Sanctions Act (CAATSA) if India went ahead with the deal. The US wanted India to resort to US-made alternatives such as The Patriot or the THAAD systems and wanted to assume the position of India's primary defence partner. It's also essential to note that the US, under Donald Trump’s first term, was sanctioning any major defence deals with Russia and had warned states not to engage in defence partnerships with Russia. 

India, however, did proceed with the deal, resisting the pressure posed by the US by asserting its strategic autonomy and the sovereign right to make decisions in favour of its own national security considerations. To further navigate this complex geopolitical landscape, India also engaged in significant lobbying efforts within the US Congress to garner bipartisan support for a waiver from CAATSA sanctions. In a significant development in 2022, the US House of Representatives formally passed a legislative amendment that effectively granted India a waiver from CAATSA sanctions specifically for the S-400 purchase. 

The strategic threat perception of India preceded the rationale for sticking to the deal of acquiring S-400 missile defence systems. In an increasingly hostile neighborhood, with conflict looming on two sides of the border, India resorted to investing in a robust missile defence system to counter the threat of long-range ballistic missiles posed by Pakistan as well as China. Furthermore, China's deployment of its own S-400 air defence systems along the Line of Actual Control (LAC) heightened India's urgency to acquire a comparable or superior system to address any potential asymmetry in air defence capabilities along their shared border. As the security dilemma of South Asia heightened, China’s defence systems were perceived as an offensive threat by India, thereby prompting it to modernise its own air-defence system. 

Figure 2: In the latest war with Pakistan, India deployed the indigenously developed Akash missile on the S-400 surface-to-air missile defence system (Source- Deccan Herald)

The delivery of the S-400 squadrons to India commenced in December 2021, with the first squadron being received and subsequently deployed along the Line of Control (LoC) in the Pathankot region. This deployment was primarily aimed at bolstering the air defences in the sensitive Punjab-Jammu & Kashmir sector. The second operational squadron was delivered in July 2022 and strategically deployed along the Line of Actual Control (LAC) in the Sikkim sector, focusing on the potential threat from China. The third squadron followed, arriving by February or March 2023, and was deployed in the Rajasthan-Gujarat sector, providing coverage over the western border with Pakistan. It is expected that the fourth squadron will be received by the end of 2025, and the fifth will be received in 2026. The delays in the delivery of the last two squadrons can be attributed to the Russia-Ukraine war. 

Beyond addressing specific threats, the S-400 is a crucial component in bolstering India's overall multi-layered air defence capabilities. The system is designed to serve as the long-range tier in this network, complementing existing short and medium-range systems such as the indigenously developed Akash missile system and the Barak-8 system developed in collaboration with Israel. 

Proposal for the joint production of S-500

The S-400 missile defence system proved to be a very significant component of India’s defence against Pakistan’s airstrikes in the recent war. The success of this system has prompted the question of further development of this series of surface-to-air missile defence systems. In the midst of this development, renewed calls for joint production of the next generation of this system have been made to India from Russia.  

One squadron of S-500 has been in service in Russia since 2001. With an operational range of approximately 600 kilometers, the S-500 is designed to intercept a broad spectrum of aerial threats, including not only aircraft, cruise, and ballistic missiles but also hypersonic missiles and even low-orbit satellites. It reportedly possesses the ability to simultaneously track up to ten ballistic supersonic terminal ICBM warheads and hypersonic missiles. A key advancement over the S-400 is the S-500's capability for exo-atmospheric interception, extending its reach into near space to counter emerging threats like hypersonic glide vehicles and intercontinental ballistic missiles. Its advanced radar systems can reportedly detect targets at distances up to 2,000 kilometers, providing enhanced situational awareness. Russia claims that the S-500 can intercept all types of modern hypersonic weapons, a capability that has reportedly been successfully tested.

Strategically, the S-500 holds immense significance, particularly in countering the growing threat of hypersonic weapons and maintaining air superiority in contested environments. Acquiring this new set of defence systems could prove to be extremely beneficial for India in deterring strategic threats posed by China and Pakistan. Additionally, this could also incentivise indigenous production of defence infrastructure that India now aims to prioritise. Jointly producing an S-500 missile defence system with Russia would also place India among the list of significant defence equipment producers in the world. 

India’s indigenous defence production has seen a massive boost in the past few years as well, reaching a record 152,000 USD in 2023-24. Defence exports also saw a record hike in 2024-25. This growth is attributed to the successful development and production of various indigenous platforms and systems, including the Dhanush Artillery Gun System, LCA Tejas aircraft, and Akash Missile System, which was also used to counter Pakistan’s airstrikes into Indian territory in the recent conflict. 

Despite the fact that joint production of the new missile system could add to India’s defence credibility and capacity while also giving India a stronger hand over the maintenance and future upgrades of the technology, India would still need to keep its balancing act. Jointly producing a defence system with Russia is a more substantial commitment than entering into an acquisition deal. Hence, it becomes all the more important for India to strategically balance this stronger commitment with Russia and its enduring bilateral partnership with the United States. The potentially high cost of the S-500 system is also a factor that India will need to consider, especially given its strong emphasis on indigenous development and the financial resources required for its ambitious modernization plans. 

Whether India decides to enter into the deal for the joint production of S-500 systems with Russia depends on many variable factors. However, the lesson learned from this new-age conflict with Pakistan is that these surface-to-air missile defence systems have become a crucial component of the defence infrastructure in contemporary times.