Russia has reportedly confirmed that the fourth squadron of the ‘Triumf’ S-400 long-range air defence system will be delivered to the Indian Air Force (IAF) by the end of May 2026. The delivery timeline coincides with the Operation Sindoor anniversary—the military conflict with Pakistan last year that proved the missile system’s worth to the nation.
Moscow's battle-proven mobile surface-to-air missile (SAM) system was sought by India in 2015, and a deal was inked during Vladimir Putin’s visit to India in October 2018. The agreement is for the delivery of five regiment sets, costing ₹40,000 crore and three have been delivered so far. The S-400 has been incorporated into India's multi-layered ‘Sudarshan Chakra’ defence system and proved its worth during the four-day face-off with Pakistan. India's first S-400 squadron became operational in December 2021 and was deployed in Punjab.
Quoting a senior defence official familiar with the bilateral talks involving the two time-tested allies, Defence Security Asia reported that the remaining deliveries of the S-400 systems are scheduled to be completed by 2027. The fourth will be delivered in 2026, while the final unit will take another year to reach New Delhi, the report added.
The lethal ‘Triumf’ batteries
Each S-400 squadron integrates a reinforced command-and-control centre, the 91N6E Big Bird long-range surveillance radar with a detection range of nearly 600 kilometres, and the 92N6E Grave Stone engagement radar, along with mobile launchers. The 91N6E radar can track targets based on their size and speed, with smaller ballistic targets detected at shorter ranges and larger aircraft, such as strategic bombers, tracked from much farther away.
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The system employs a diverse missile inventory—including the 40N6 with a 400-kilometre range, the 48N6 at 250 kilometres, the 9M96E2 at 120 kilometres, and the 9M96E at 40 kilometres—allowing operators to carry out cost-effective, layered interceptions depending on the threat. Capable of engaging targets at altitudes of up to 30 kilometres and at terminal speeds exceeding Mach 14, the S-400 significantly restricts enemy airspace options by forcing hostile aircraft to fly lower, farther away, or with reduced weapon loads.
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Meanwhile, reports have previously stated that the war in Europe has made the Russian weapon system even more lethal. Building on the lessons learnt from the Ukraine war, in which Moscow successfully deployed air defence systems (including for thwarting attacks with US-made ATACMS), Russia is modernising the S-400 to neutralise threats with much greater effectiveness.
"The speed of change allows us to respond without delay to new challenges. One of these responses is the enormous modernisation potential of the S-400 air defence missile system, which allows us to quickly mitigate emerging threats during the special military operation. Triumf has acquired new capabilities and properties that are generally not characteristic of air defence systems," Yan Novikov, CEO of Almaz-Antey Group, had said. Almaz-Antey is the Russian state-owned defence conglomerate that designed, developed, and currently produces the S-400 system.
A testament of Indo-Russian bond
News agency PTI, in an early October 2025 report, claimed India is considering procuring additional units of the air defence system and the topic may figure in talks between New Delhi and Moscow when Putin visits India in December. Later that month, ANI added that the IAF is looking to buy missiles worth around ₹10,000 crore to boost the country's air defence capabilities.
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Both the previous Donald Trump and Joe Biden administrations had warned India that proceeding with the S-400 purchase would invite sanctions under the provisions of the Countering America's Adversaries Through Sanctions Act (CAATSA). CAATSA is legislation that provides for sanctions to be imposed on companies in other countries trading with entities in Russia, Iran, and North Korea.