Platform profile · India · Submarine-launched ballistic missile family · Strategic Forces Command / Indian Navy
K-series SLBMs
OngoingINS Aridhaman entered service on 3 April 2026, expanding the SSBN fleet while K-4 integration remains under validation.
On 3 April 2026, India commissioned INS Aridhaman, its third nuclear-powered ballistic-missile submarine, adding another prospective K-series deployment platform. A reported K-4 launch from INS Arighaat on 23 December 2025 followed the submarine's first K-4 firing on 27 November 2024, although reporting indicated that further validation was required before full operational status. The operational shorter-range K-15 Sagarika reaches 700-750 km, while the solid-fuel K-4 extends public estimates to approximately 3,500 km. The longer-range system matters because it gives India's sea-based retaliatory force greater patrol flexibility and target coverage against China while retaining coverage of Pakistan.
Updated 3 Apr 2026
Verified figures
Specifications
| Specification | Value |
|---|---|
| Range (K-15 Sagarika) | 700-750 km ↗ |
| Length (K-15 Sagarika) | 10.8 m ↗ |
| Diameter (K-15 Sagarika) | 0.8 m ↗ |
| Launch weight (K-15 Sagarika) | 5,500-6,300 kg ↗ |
| Payload (K-15 Sagarika) | 500-800 kg ↗ |
| Powerplant (K-15 Sagarika) | 2-stage solid-propellant rocket ↗ |
| Range (K-4) | Approximately 3,500 km ↗ |
| Powerplant (K-4) | Solid-fuel rocket ↗ |
| Missile tubes (first two Arihant-class boats) | 4 tubes; each accommodates multiple K-15 missiles or 1 K-4 missile ↗ |
| Missile tubes (later Arihant-class boats) | 8 tubes for K-4 missiles ↗ |
Spec sources: missilethreat.csis.org ↗ · indianexpress.com ↗ · armscontrol.org ↗
Changelog
Program timeline
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The Indian Navy commissioned INS Aridhaman, its third nuclear-powered ballistic-missile submarine, at Visakhapatnam.
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India reportedly fired the approximately 3,500 km K-4 from INS Arighaat in the Bay of Bengal, with further tests still required before induction.
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India conducted the first K-4 launch from INS Arighaat off Visakhapatnam, with the missile reportedly covering nearly its full 3,500 km range.
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The Indian Navy commissioned the second Arihant-class submarine INS Arighaat at Visakhapatnam to strengthen India's nuclear triad.
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INS Arihant completed a successful SLBM user-training launch to a predetermined range in the Bay of Bengal, striking with high accuracy and validating all operational and technological parameters.
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India conducted its second K-4 launch of January 2020 from an underwater platform, testing the approximately 3,500 km missile before planned serial production.
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India announced that INS Arihant had completed its first deterrence patrol, establishing an operational sea-based leg of the nuclear triad.
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