India Fourth S-400 Sudarshan Chakra: India is getting ready to receive the fourth squadron of the Russian-made S-400 air defence system in the coming weeks. Reports say parts of the system started sailing from Russia last week, and the delivery is expected around May. The Indian Air Force already has three S-400 squadrons in service. The system is also being talked about as the “Sudarshan Chakra.”
India signed the original deal with Russia in 2018 for five S-400 squadrons. Reuters said the deal was worth about $5.43 billion, while India Today put it at around Rs 35,000 crore. The fifth and final squadron under that first contract is still due later this year, though some reports say it could slip into 2027 depending on transport and supply timing. In March 2026, India also approved five more Russian S-400 systems. If all of them are eventually delivered, India’s total S-400 inventory could rise to 10 squadrons.
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Why the S-400 matters so much
The S-400 is a big part of India’s air defence plan because it can spot and hit many kinds of threats from far away. According to Reuters and India Today, India sees it as useful for modern military needs after the 2025 conflict with Pakistan and as part of a wider push to improve air defence. The system can track aerial threats from up to 600 km and hit targets at up to 400 km, which is why it is viewed as one of the strongest systems in India’s armoury.
India Today says the S-400 battery includes 16 vehicles in one squadron, with launchers, radar units, control centres and support vehicles. The system uses four types of missiles. The long-range 40N6E is meant for high-value flying targets. The 48N6 works against faster aircraft and some ballistic threats. The 9M96E2 is for medium-range use, and the shorter 9M96E is for low-flying cruise missiles, drones and precision weapons. This makes the system flexible. It can deal with more than one threat type at the same time.
Where India has placed it and how it fits in war
India has already placed its S-400 squadrons in very sensitive areas. One unit guards the Siliguri Corridor, also called the Chicken’s Neck, which links the Northeast to the rest of India. Another sits near Pathankot to cover Jammu and Kashmir and Punjab. A third is deployed on the western border to protect Rajasthan and Gujarat. The fourth unit, once it arrives, is expected to help the western front even more.
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The system also became more famous after Operation Sindoor in May 2025. Reuters reported that India launched strikes on targets in Pakistan and Pakistan-administered Kashmir, and the four-day clash became the worst between the two nuclear-armed neighbours in many years. Indian reports said the S-400 played an active role during that fighting and helped counter Pakistani missiles and aerial threats. India Today said the system proved itself during the operation and was used alongside indigenous air defence assets.
India’s wider defence links
The S-400 is not only in India. Reuters and CSIS reporting show that Russia, China, Turkey and Belarus also operate the system in different ways. Turkey’s purchase brought major trouble with the United States, while Belarus has also received S-400 units from Russia. China got its first deliveries in 2018. That wider spread has made the S-400 one of Russia’s most watched defence exports.
The deal also fits into the bigger India-Russia defence picture. Reuters reports that India and Russia are still working together on BrahMos missile exports, AK-203 rifle production in India, and Su-30 life-extension upgrades. Reuters also said in March 2026 that India approved more military purchases, including S-400 systems, as part of a larger defence build-up after tensions with Pakistan and China. So the S-400 is not just one weapon. It is part of a much bigger defence friendship that is still growing.
