Why in news?
India conducted a successful full-range test from INS Arighaat in the Bay of Bengal on December 23, 2025, off Visakhapatnam, boosting sea-based deterrence. A prior test from the same submarine occurred in November 2024.​​
Key Facts about the K-4 Missile
- Type: Intermediate-range SLBM (Submarine-Launched Ballistic Missile)
- Developer: Defence Research and Development Organisation (DRDO)
- Manufacturer: Bharat Dynamics Limited
- Launch Platform: Arihant-class nuclear-powered submarines
- Range: ~3,500 km
- Warhead Capacity: Up to 2,500 kg (nuclear-capable)
- Engine: Two-stage solid rocket motor
- Guidance System: Inertial navigation + GNSS (mid-course), TERCOM (terminal)
Strategic Importance
- Sea-Based Deterrence: The K-4 enhances India’s second-strike capability, meaning India can retaliate even if land-based systems are compromised.
- Stealth Advantage: Submarine launch allows India to strike while remaining hidden underwater, making it harder for adversaries to detect.
- Part of Nuclear Triad: Complements land-based (Agni series) and air-based nuclear delivery systems, completing India’s nuclear triad.
- Extended Reach: With 3,500 km range, India can target adversaries deep inside hostile territory from the Indian Ocean.
Comparison with Other Indian Missiles
| Missile |
Type |
Launch Platform |
Range |
Warhead Capacity |
Status |
| K-4 |
SLBM |
Arihant-class submarines |
3,500 km |
~2,500 kg |
Tested, awaiting induction |
| K-15 (Sagarika) |
SLBM |
Arihant-class submarines |
750 km |
~1,000 kg |
Operational |
| Agni-III |
Land-based IRBM |
Road/Rail mobile launchers |
3,500 km |
~2,500 kg |
Operational |
| Agni-V |
Land-based ICBM |
Road/Rail mobile launchers |
5,000–5,500 km |
~1,500 kg |
Operational |
Challenges & Next Steps
- Operational Induction Pending: The K-4 still requires further test-firings before full deployment.
- Submarine Fleet Expansion: India’s Arihant-class submarines are limited in number; expanding the fleet is crucial for sustained deterrence.
- Strategic Balance: Enhances India’s deterrence posture against regional adversaries, but also raises questions about arms race dynamics in South Asia.
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