New Delhi/IBNS: Amid ongoing diplomatic tensions with Canada, India has quietly launched its fourth nuclear-powered ballistic missile submarine (SSBN) at the Ship Building Center (SBC) in Visakhapatnam, in a move to bolster the South Asian major's nuclear deterrence capabilities, reports said.

According to reports, India’s second SSBN, INS Arighaat, was officially commissioned on August 29, 2024, by Defence Minister Rajnath Singh.

The third SSBN, INS Aridhaman, is expected to be commissioned next year.

On Oct. 9, the Cabinet Committee on Security (CCS) approved the construction of two additional nuclear-powered attack submarines, signaling India's intent to strengthen its naval presence in the Indo-Pacific region.

The Modi government, while maintaining discretion on its nuclear strategy, quietly launched its fourth SSBN, codenamed S4, on Oct. 16, just a day after Defence Minister Singh inaugurated a Very Low Frequency (VLF) Naval Station in Telangana to enhance communication with India’s strategic naval assets.

The newly launched S4 is approximately 75 percent indigenous and is armed with K-4 ballistic missiles, which have a range of 3,500 kilometers.

These missiles are launched from vertical systems, marking an upgrade from the earlier INS Arihant, which carries shorter-range K-15 missiles.

With unlimited endurance, India’s SSBN fleet can remain submerged for extended periods, limited only by food, crew fatigue, and maintenance.

Both INS Arihant and INS Arighaat are already on deep-sea patrols, and India is set to acquire a Russian Akula-class attack submarine on lease by 2028.

India’s SSBN fleet has followed a structured naming convention: INS Chakra, the first leased nuclear attack submarine, was designated as S1, followed by INS Arihant (S2), INS Arighaat (S3), and INS Aridhaman (S4).

The newly launched S4 is the last of this class, with its formal name pending.

Future SSBN classes are expected to have double the displacement of the Arihant class and carry missiles with ranges exceeding 5,000 kilometres.

The Modi administration’s focus on submarine-based nuclear deterrence stems from the vulnerability of aircraft carriers to China’s long-range missiles, such as the Dong Feng-21 and Dong Feng-26, which could severely limit their effectiveness.

As a result, the government has prioritized the development of nuclear attack and ballistic missile submarines over the Indian Navy’s third aircraft carrier.

Additionally, the sixth diesel-electric attack submarine of the Kalvari class, INS Vagsheer, will be commissioned in December.

Looking ahead, India plans to collaborate with the French Naval Group to construct three advanced diesel-electric attack submarines at Mazagon Dockyards.

With China deploying 10-11 warships in the Indian Ocean each month and expected carrier-based patrols by 2025-26, India’s strategic submarine fleet is poised to play a critical role in securing the Indian Ocean Region (IOR) and countering potential threats.