India signed a $5.43 billion contract with Russia in 2018 for the procurement of five S-400 Triumf air defence systems. The deal aims to significantly enhance India's airspace defence capabilities, particularly against threats from China and Pakistan.

As of 2025, four of these systems have been delivered and integrated into India's network, with the final fifth system scheduled for delivery in 2026. The contract faced multiple delays, partly due to geopolitical tensions and supply chain issues linked to the Russia-Ukraine war.

The S-400 systems have proven highly effective during recent military operations, notably Operation Sindoor in May 2025, where they provided critical interception capabilities against incoming missiles, reinforcing India's deterrence posture.

Impressed by the performance of these systems, India is actively exploring the procurement of additional S-400 units. Furthermore, there is growing interest in acquiring the more advanced Russian S-500 Prometheus air defence systems, which promise enhanced capabilities over the S-400.

Negotiations between India and Russia are ongoing for additional deliveries beyond the initial five S-400 units. A follow-on clause in the original 2018 contract permits acquiring more systems under similar financial terms, subject to inflation or currency fluctuations.

Russia has assured India that the remaining units of the original deal will be completed by 2026 or 2027, with discussions about further acquisitions including the S-500 systems progressing alongside.

The defence partnership between the two countries remains strong despite external pressures such as potential U.S. sanctions under CAATSA (Countering America's Adversaries Through Sanctions Act), which have so far not been enforced against India's S-400 dealings.

The Indian defence establishment views the S-400 and prospective S-500 systems as critical assets for long-range air and missile defence.

These systems can detect, track, and neutralise a wide range of aerial threats, including fighter jets, UAVs, cruise missiles, and ballistic missiles, at ranges exceeding 400 km.

The acquisition aligns with India's broader strategy to bolster its indigenous Project Kusha air defence program and modernise fighter fleets such as the Su-30MKI that have been central during recent cross-border conflicts.

India is not only set to complete the delivery of its initial S-400 Triumf units by 2026 but is also actively pursuing further acquisitions of advanced Russian air defence systems, including the S-500 Prometheus, to maintain and extend its strategic deterrence and defensive capabilities in a challenging regional security environment.

IDN (With Agency Inputs)