K-4 Missile

Full Specifications

K-4 Missile: India’s Intermediate-Range Submarine-Launched Ballistic Missile

The K-4 missile, also known as Kalam-4, represents a significant advancement in India’s strategic deterrence capabilities. As an intermediate-range submarine-launched ballistic missile (SLBM), it forms a critical component of the country’s nuclear triad, providing a survivable second-strike option from the sea. Developed to enhance the operational flexibility of India’s Arihant-class nuclear submarines, the K-4 addresses limitations of shorter-range predecessors like the K-15 by enabling strikes against distant strategic targets while maintaining the stealth advantages of underwater launch.

Manufacturer

The K-4 was designed and developed by India’s Defence Research and Development Organisation (DRDO) in collaboration with other defense entities. It draws technological heritage from the land-based Agni-III missile program. The missile entered limited operational induction with the Indian Navy in 2024, with successful tests conducted from the INS Arighaat and other Arihant-class submarines.

Speed and Range

The K-4 achieves hypersonic speeds during its ballistic trajectory, powered by a two-stage solid rocket motor. Its operational range is approximately 3,500 km, allowing it to reach key strategic areas from patrol positions in the Indian Ocean. This range provides substantial standoff capability compared to earlier Indian SLBMs.

Cost/Price

As a strategic military system not available for commercial sale, the K-4 has no public market price. Analyst estimates for per-unit production costs, including amortized R&D, typically range from $10–20 million USD, though exact figures remain classified due to the program’s sensitivity.

The missile measures about 12 meters in length, 1.3 meters in diameter, and weighs roughly 17 tonnes at launch. It can deliver a nuclear warhead of up to 2,000–2,500 kg. Its guidance system combines inertial navigation (INS) with GPS/NavIC satellite updates and TERCOM for terminal accuracy, achieving a circular error probable (CEP) of less than 10 meters. This precision, along with maneuverable re-entry capabilities, enhances its ability to penetrate potential missile defenses.

The K-4 strengthens India’s nuclear posture by ensuring credible deterrence through submarine-based platforms that are difficult to detect and neutralize preemptively. Its solid-fuel design supports rapid launch readiness, contributing to the overall survivability of India’s strategic forces.