Defence systems in UPSC Prelims: 16 questions, 12 of them in the last three papers
UPSC asked 4 defence systems questions from 2016 to 2023, then 12 from 2024 to 2026. What those 16 questions test, why the name of a system is so often the trap, and a plan built on them.
Most aspirants treat defence as a current affairs afterthought: a list of missile names, exercise partners and ship launches, skimmed in the last month. For years that was a fair bet, because UPSC barely asked about it. The last three papers changed that. Defence systems went from an occasional question to a regular part of the paper.
This post looks at the 16 questions on missiles and defence systems asked from 2016 to 2026 and turns them into a plan.
What the numbers say
Three things stand out.
It took off in 2024. The first eight papers had 4 questions between them. The last three had 12: 3 in 2024, 3 in 2025 and 6 in 2026.
| Year | Questions |
|---|---|
| 2016 | 1 |
| 2017 | 0 |
| 2018 | 1 |
| 2019–2021 | 0 |
| 2022 | 1 |
| 2023 | 1 |
| 2024 | 3 |
| 2025 | 3 |
| 2026 | 6 |
It used to skip years. Only 7 of the 11 papers had a defence systems question. All four gaps (2017, 2019, 2020 and 2021) came before 2022. Every paper since has had at least one.
The format has changed with it. 5 of the 16 were single-answer questions, such as “what is THAAD”. The other 11 gave you statements, pairs or a list to judge. Three of the first four questions were single-answer. Only two of the last twelve were. All three “how many are correct” questions came in 2024 or 2025.
What UPSC is really testing
By our count, the 16 questions fall into five groups:
- Platforms: 4 questions. What INS Astradharini is, which fighters count as fifth generation, what the Dornier-228, IL-76 and C-17 are used for, and which hardware is made in India.
- Missiles and missile defence: 4. THAAD, the Fractional Orbital Bombardment System, ballistic versus cruise missiles (with Agni-V and BrahMos), and Mission Sudarshan Chakra.
- How the forces are organised: 3. Equivalent ranks across the Army, Air Force and Navy, the duties of the Chief of Defence Staff, and Army Corps headquarters.
- Drones and stealth: 3. What all UAVs can and cannot do, how drone swarms communicate, and stealth technology.
- Explosives and bomb disposal: 2. CL-20, HMX and LLM-105, and the new BIS standard for bomb disposal systems.
The working title for this post had “exercises” in it. The data didn’t support it: none of the 16 questions in this area asked about a military exercise. Ships were rare too. Only INS Astradharini was a question of its own, though an Akula-class submarine appeared as one item in a 2026 list.
What the questions did ask was what kind of thing a system is. A torpedo vessel or a submarine. A transport plane or a fighter. A cruise missile or a ballistic one.
The trap most questions share
The wrong option is what the name sounds like. “Astradharini” carries “astra”, a weapon, so it sounds like a combat vessel. It is a torpedo launch and recovery vessel used to test underwater weapons. “Orbital” bombardment sounds like space exploration. It is a way of delivering a warhead. “Chief of Defence Staff” sounds like the top commander. The post has no command over the Service Chiefs.
Here is how the trap was set in the questions where it came from the name or something familiar nearby. All of these have official answers:
| Question | What it actually is | What the trap borrowed |
|---|---|---|
| INS Astradharini (2016) | Torpedo launch and recovery vessel | “Astra”, a weapon |
| THAAD (2018) | An American anti-missile system | Its deployment in South Korea |
| FOBS (2022) | A warhead put in low orbit, brought down over a target | The word “orbital” |
| Rafale (2024) | A 4.5-generation fighter | India’s most modern fighter |
| CDS (2024) | Chairman and adviser, with no command | The word “Chief” |
| Commodore (2024) | Navy equal of a Brigadier | Looks like “Commander” |
| IL-76 (2025) | A heavy, subsonic transport plane | A big Russian-origin aircraft |
| HMX (2025) | A military explosive | Its use in some rocket propellants |
The statement sets had a second trap: in 3 of them, every statement or item was false. Ballistic versus cruise missiles (2023) swapped the descriptions of the two. The fighter question (2024) listed three aircraft and none was fifth generation. The UAV question (2025) said “all types” in every statement. Fixed-wing drones can’t hover or land vertically, and many UAVs run on fuel, not only batteries.
The 2026 questions repeat the pattern, though their answers come from a provisional key. India operated an Akula-class submarine, so it sounds Indian-made. Srinagar is a major Army base, so it sounds right for 33 Corps. Close India-Russia defence ties made a Russian partner for the BIS standard sound believable.
How to prepare
1. For each system, write what type it is. Ship or submarine, fighter or transport, ballistic or cruise, Indian or foreign. One line each. “THAAD: American anti-missile system” is the whole answer to a past question.
2. Learn the pairs UPSC can swap. Ballistic missiles are rocket-powered only at the start and then fall freely. Cruise missiles are powered throughout flight. Agni-V is a long-range ballistic missile. BrahMos is a supersonic cruise missile. The 2023 question swapped both.
3. Know what puts a fighter in the fifth generation. Full stealth, supercruise and sensor fusion, as in the F-22, F-35 and J-20. Rafale, MiG-29 and Tejas Mk-1 are not fifth generation.
4. Learn the organisation basics. The three-service rank table, the role of the CDS and the main Army Corps headquarters. These have come up 3 times since 2024 and need no current affairs at all.
5. Distrust “all”. Multirotor drones are only one type of UAV. If a statement says every drone can hover or land vertically, test it against a fixed-wing drone. If it says all run on batteries, remember petrol and jet engines.
6. Keep a note on new missions and standards. For each, write who runs it and what it covers. Then solve the missiles and defence systems questions and the wider defence and security tech topic.
What to skip: exercise names and partner countries, ship launch dates and missile test dates. None of the 16 questions turned on them.
Two questions that show the pattern
2023 · Missiles. Two statements: ballistic missiles fly on jet power at subsonic speed while cruise missiles are rocket-powered only at first; Agni-V is a medium-range cruise missile while BrahMos is an ICBM. Neither is correct. Each statement takes two true descriptions and swaps them, so every phrase looks familiar. See the question
2024 · Organisation. Which of three duties belong to the CDS as head of the Department of Military Affairs? Permanent Chairman of the Chiefs of Staff Committee, and Principal Military Adviser to the Defence Minister on tri-service matters. Not military command over the three Service Chiefs. The title sounds like a commander, and the post was designed without that power. See the question
For how defence fits into the 2026 paper as a whole, see our 2026 paper analysis. Biotechnology questions set the same name-based trap, and we wrote about them here. For the other high-yield areas, see the must-do list.