S-400: Adding a longer reach

By December 2021, India had begun receiving the Russian S-400 air-defence system. The equipment arrived under a purchase agreed three years earlier, bringing a new long-range system into a military relationship built over decades. It also brought a diplomatic question: how India would proceed with Russian arms purchases while deepening ties with the United States. [1]

The acquisition was substantial and still unfolding. Outlook reported on 8 September 2026 that four of the five contracted units had been delivered, with the fifth scheduled for November. That was a dated delivery checkpoint and a future timetable, rather than confirmation that the entire order had been fulfilled. [5]

A contract within an older partnership

India and Russia announced the S-400 contract at their October 2018 summit. Their joint statement placed defence cooperation within a relationship that included the Soviet-era 1971 treaty, the 1993 friendship treaty and the strategic partnership declared in 2000. The Modi government made this particular purchase; the institutional relationship supporting it was much older. [2]

The defence ministry’s 2019 review identified five contracted squadrons. It expected the first equipment to be inducted in mid-2020. The later arrival shows why procurement accounts need to retain their original dates: an announced schedule is evidence of what was intended, not of what was delivered. September 2026 reporting put the contract’s value at $5.43 billion. [3] [1] [5]

The decision proceeded amid the possibility of American sanctions, as contemporary reporting described. In a parliamentary reply on 3 December 2021, the defence ministry said India made sovereign procurement decisions according to threat perceptions, operational needs and technological considerations. That stated the government’s position; it did not remove the practical dependence on a foreign supplier completing the order. [1] [4]

Equipment, operations and upkeep

The ministry described S-400 as a system intended to provide air defence over a large area. Its acquisition added to the country’s existing equipment rather than creating air defence from scratch. During his May 2025 visit to Adampur, Modi spoke of S-400 operating alongside older systems and the indigenous Akash in the context of Operation Sindoor. [4] [6]

That address forms part of the government’s account of the operation. It does not, by itself, establish a verified tally of aircraft intercepted by a particular system. The procurement record supports the addition of equipment; assessing individual engagements requires evidence about those engagements. [6]

Keeping the equipment usable remained another task. In August 2025, the Defence Acquisition Council approved the need for a comprehensive annual maintenance arrangement for S-400. The approval concerned support for the system already acquired, and was distinct from evidence that a new maintenance contract had been signed. [7]

By September 2026, the order had supplied most of its intended units, while the last delivery remained on the calendar. Operating the received systems and securing the remainder were now parallel responsibilities: one for the force using them, the other for the governments and supplier completing the purchase. [5]