Russia has submitted its detailed proposal in response to India's tender for acquiring five additional squadrons of the S-400 Sudarshan long-range air defence system for the Indian Air Force, marking a significant step in the procurement process, according to an ANI report.

"The Russian response to the Indian tender has been received, and it is being processed at the moment. The project is estimated to cost over Rs 50,000 crore," defence sources told ANI.

India cleared the proposal to procure five more S-400 squadrons in March, shortly after Operation Sindoor.

The additional systems are expected to bolster the country's layered air defence capabilities, particularly along its eastern and western fronts.

India already operates four S-400 squadrons

The Indian Air Force currently operates S-400 systems acquired under a 2018 agreement with Russia.

Under the original contract, India ordered five squadrons, of which four have been delivered. The fifth and final squadron is expected to be delivered by November this year, according to defence sources.

If the new contract is finalised, deliveries of the five additional squadrons are likely to begin around three years after the agreement is signed.

S-400 played key role during Operation Sindoor

The S-400 gained renewed prominence during Operation Sindoor, when the system was deployed as part of India's air defence network amid Pakistani aerial activity.