What are Su-57 Jets and the S-500 Air Defence System—Why did India say no to Russia?

In a significant move, Russia has offered to make its fifth-generation stealth fighter jet, the Su-57, to the Indian Air Force. This innovative proposal was announced on June 4, 2025, to mark the most comprehensive technology transfer deal has ever been offered to India in the defence sector. In addition, Russia has also reportedly offered joint production of the S-500 to India after the successful deployment and performance of the S-400 system against Pakistan during 'operation sindor', but further negotiations and decisions are still pending.

What is the Russia's Su-57 Jets?

The aircraft features state-of-the-art radar systems, internal weapon bays to reduce external visibility, and an angular design that helps deflect radar waves. Its curved air intakes also protect the engine blades from the detection of the radar system, according to a report in Network 18.

Without using afterburners, it can fly at supersonic speeds for extended periods. Built with stealth capabilities, the jet is harder for adversaries to detect and comes equipped with a versatile weapons package designed for dominance in the air and precision strikes on targets.

These design elements collectively minimise both radar and infrared signatures, making the aircraft difficult to detect or track. It is regarded as a technologically advanced and combat-ready system that could be smoothly adapted into the Indian Air Force’s operations.

What is Russia's S-500 Air Defense System?

The S-500, quite popular as Prometheus, marked as significant air defence technology. It is designed to counter upcoming threats such as hypersonic glide vehicles, high-speed drones, and low Earth orbit (LEO) satellites, which are beyond the capability of the S-400 defence system.

The detection range of this system is up to 2,000 km for ballistic targets, 800 km for airborne targets. And, interception range of the Defence System is 600 km for ballistic and 400 km for airborne targets. In addition, it can hit 10 target at a time with response 3-4 seconds faster than S-400.

Why India says no to Russia?

According to Indian air force officials, the Su-57 of Russia was too expensive, poorly engineered with old and unreliable engines. Previously, at the time of deal, Sukhoi was developing two Su-57 versions, one for Russia and another was designed for India. The Russian variant was reportedly more basic, while the Indian version was expected to include Indian-made avionics and support a broader range of weapons. However, the Indian version of this system had not advanced beyond design drafts, and also progress on the variant's development was slow and disappointing.

Based on transcripts from meetings held in December 2013 and January 2014, obtained by Business Standard, Indian Air Force and defence ministry officials identified at least four major “shortfalls … in terms of performance and other technical features”.

Additionally, India's Advanced Medium Combat Aircraft (AMCA) project is accelerating as officials appear more to focused inward, giving high-priority to homegrown. That means the Su-57 deal, even with technology transfer, is no longer appealing and effective for India.

Meanwhile, India says no to Russian S‑500 air defence system as it has already signed a $5.4 billion deal with Russia in 2018 for five units of the S‑400 system. The deal is still being fulfilled as 3 of the 5 ordered system has arrived yet, with delays due to the Ukraine war and sanctions on Russia. Therefore, it is not looking to commit to another costly Russian system until that’s completed.

In addition, India is extending its defence deal from being more Russian centric to western and indigenisation under Aatmanirbhar Bharat (self-reliance).