Which of the following statements with regard to drone swarms is/are correct ? 1. They use Terahertz band of frequency to communicate with the command centre. 2. Individual drones in the swarm can communicate with other drones in the swarm. 3. GPS Spoofing is a commonly used technique to counter drone swarm attack. Select the answer using the code given below :

(a) 1 only
(b) 2 and 3 only ✓ UPSC's answer
(c) 1 and 2 only
(d) 1, 2 and 3

Why the answer is (b)

• A drone swarm is a group of unmanned aircraft that coordinate autonomously through drone-to-drone links, sharing position and task data so the swarm keeps functioning even if some units are lost — statement 2 is correct.

• Because swarms rely on GNSS for navigation, defenders can spoof GPS signals, feeding false coordinates so the drones drift off course or land; this, along with jamming and directed-energy weapons, is a recognised counter-swarm technique — statement 3 is correct.

• Statement 1 is wrong: drones communicate over conventional radio bands (typically 2.4 GHz, 5.8 GHz, or military UHF/L/S-band and satellite links); terahertz frequencies are short-range, easily absorbed by the atmosphere and not used for command links.

• Swarm tactics featured prominently in the Nagorno-Karabakh and Ukraine conflicts and in India's own Army Day demonstrations.

• Hence 2 and 3 only, option (b).

Why the other options are wrong

(a) 1 only: Statement 1 is wrong: terahertz bands are not used for drone command links.
(c) 1 and 2 only: Statement 1 is wrong and statement 3 on GPS spoofing is correct.
(d) 1, 2 and 3: Statement 1 is wrong, so all three cannot be correct.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2026, held on 24 May 2026. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.