INS Arighat, equipped with the K-4 submarine-launched ballistic missile, boasts a range of 3,500 kilometers. The ballistic missile was test-fired on November 27 from the newly commissioned submarine in the Bay of Bengal. Although the Indian government has not made any official statements regarding the test, a Notice to Airmen (NOTAM) was issued, warning flights to avoid a 3,490-kilometer corridor. While no confirmation has been given on whether all test parameters were met, this marks the first instance of the K-4 missile being launched from a submarine; previously, it had only been tested using a submersible pontoon.
INS Arighat changes the dynamic
India’s first nuclear-powered submarine, INS Arihant, primarily served as a technology demonstrator. It is armed with K-15 missiles, which have a range of 750 kilometers—a range insufficient to reach significant targets in China, a key adversary. Even in a potential conflict with Pakistan, the K-15’s range limits its targets to the southern parts of the country. However, INS Arighat, armed with the K-4, dramatically changes this dynamic.
Submarine-launched ballistic missiles (SLBMs) aboard nuclear-powered submarines are considered the most survivable delivery system due to the inherent opacity of ocean depths. However, such systems are technologically demanding, requiring precision in stability, speed, and accuracy across both water and atmospheric environments.
Importance of K-4 ballistic missile from INS Arigha
The successful launch of the K-4 missile from INS Arighat is thus a pivotal achievement for the Indian Navy.
Nuclear experts emphasize that SLBMs must have adequate range to allow submarines to operate safely out of harm’s way. Without such range, submarines could become liabilities instead of assets. The successful test of the K-4 missile addresses this critical need, particularly given the growing tensions in the Indo-Pacific region.
INS Aridhaman also armed with K-4 ballistic missile
India is also advancing its nuclear submarine fleet, with the INS Aridhaman slated for commissioning in 2025. Equipped with the same K-4 missiles, the Aridhaman is expected to fully operationalize India’s second-strike nuclear capability. Following the Aridhaman, India plans to induct the advanced S-4 submarine and another unnamed SSBN, which will carry the more advanced K-5 missile with a range of 5,000 kilometers. A robust SSBN fleet of at least three to four submarines is necessary to maintain an effective deterrence, ensuring one submarine remains on patrol at all times.
No first use policy
This milestone occurs amid debates over India’s No First Use (NFU) nuclear doctrine. India’s NFU policy rests on three pillars: credible minimum deterrence, massive retaliation, and NFU. However, China’s growing nuclear arsenal has cast doubt on the viability of this approach. Critics argue that NFU restricts the size of India’s nuclear arsenal, further widening the capability gap with Beijing.
As India progresses toward fully operational nuclear deterrence, it faces challenges in ensuring effective communication with nuclear-armed submarines. Ballistic missile submarines do not carry live nuclear weapons onboard. Instead, missiles are kept in a disarmed state, with stringent control systems and Permissive Action Links (PALs) preventing unauthorized activation or launch. However, SSBNs primarily rely on very low-frequency communication systems, which limit the complexity of messages they can receive. This raises concerns about whether a submarine could miss critical arming or strike orders from the command authority.
With its advancements in nuclear submarines and missile technology, India is steadily building a robust and credible sea-based deterrent, reinforcing its position as a key player in regional and global strategic stability.
