UPSC Mains 2021 GS Paper 3 Q5: model answer
How is S-400 air defence system technically superior to any other system presently available in the world?
What the question wants
Explain the technical features that make the S-400 superior to other air defence systems.
How to structure it
System, superior features, caveats.
- What it is
- Technical edge
- India's use and caveats
How to think it through
Russian Triumf, made by Almaz-Antey. Range up to 400 km (40N6 missile), 600 km radar detection; four missile types for layered defence (40, 120/250, 400 km); tracks ~300 targets and engages ~36 simultaneously; targets aircraft, drones, cruise and ballistic missiles; quick deployment ~5 min; mobile; resistant to jamming; integrated with other systems. India bought five squadrons 2018 ($5.4bn), named Sudarshan Chakra; used in Op Sindoor May 2025. CAATSA risk. Compared: Patriot PAC-3 range ~160 km.
Model answer
India signed a deal for five squadrons of the Russian S-400 Triumf in 2018, worth about $5.4 billion, despite the risk of US sanctions under CAATSA. In May 2025, during Operation Sindoor, the system, called Sudarshan Chakra in Indian service, was reported to have intercepted hostile aircraft and missiles.
Why it is technically superior
- Long reach: missiles that hit targets up to 400 km away; radar that detects them at around 600 km.
- Layered defence: four missile types for short, medium, long and very long ranges in one system.
- Many targets at once: it can track about 300 targets and engage dozens simultaneously.
- Versatile: shoots down aircraft, drones, cruise missiles and some ballistic missiles.
- Mobile: ready to fire within minutes of arriving.
- Jam-resistant radars and integration with other air defence layers.
- The US Patriot PAC-3 has a shorter reach of roughly 100–160 km.
Caveats
- Stealth aircraft may be harder to detect.
- Dependence on Russia for spares, and sanctions risk.
It extends India's air shield deep across its borders, but it is one layer, not the whole wall.
Draw: Concentric circles of 40, 120, 250 and 400 km around a launcher.
Keywords, cases and data to drop in
S-400 Triumf, Almaz-Antey, 400 km, 600 km radar, 40N6, layered defence, 300 targets, 2018 deal $5.4 bn, CAATSA, Sudarshan Chakra, Operation Sindoor 2025, Patriot PAC-3.
Where most answers lose marks
- Writing about geopolitics only. The question asks for technical superiority.
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Question text as printed in the official UPSC Civil Services (Main) question paper. The model answer is original Battle IAS work; use it to learn structure, not to memorise.
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