Context: Recently, The Central Bureau of Investigation (CBI) filed two chargesheets against naval officers, for sharing details of the ongoing modernization project of India’s Kilo Class submarines.

Submarines in India

• India has 15 conventional diesel-electric submarines, classified as SSKs, and one nuclear ballistic submarine, classified as SSBN.
• The Navy's hull classification symbols for ballistic missile submarines are SSB and SSBN.
• SSBN: SS denotes submarine (or submersible ship), the B denotes ballistic missile, and the N denotes that the submarine is nuclear powered.
• SSK: SS indicated that the vessel was a submarine, and the K suffix that it was a hunter-killer. 

All these submarines are of 3 types
Shishumar class vessels

• India has 4 such vessels.
• They were bought and then built in India in collaboration with the Germans starting 1980s.

Kilo class diesel-electric submarines (Sindhughosh class)

• India has 8 such sub-marines.
• They were bought from Russia between 1984 and 2000.

Kalvari Class

• India has 3 Kalvari Class submarines (Kalvari, Khanderi and Karanj) in service and two such submaines is under- construction (Vela and Vagir).
• INS Kalvari is the first of the six Scorpene class submarines built under Project 75.
• They are built at India’s Mazagon Dock in partnership with France’s Naval Group.

Arihant Class

• INS Arihant is a nuclear-powered ballistic missile submarine (SSBN), built indigenously.
• A second SSBN, INS Arighat, an upgraded version of Arihant, is likely to be commissioned within the next few months.

Nuclear Submarines

• India is among six nations that have SSNs, alongside the US, UK, Russia, France, and China.
• India got its first SSN in 1987 from the Soviet Navy, which was decommissioned in 1991.
• In 2012, India got another Russian SSN on a ten-year lease, called INS Chakra 2, which has been returned to Russia.
• India is taking two SSNs on lease from Russia, the first of them is expected to be delivered by 2025.
• India is building at least two larger SSBNs that will have bigger missiles, called S4 and S4* projects. The SSBNs are expected to be commissioned before 2030.

Challenges to Indian Naval Buildup

• China’s Naval Prowess: India’s underwater fleet continues to lack the requisite teeth despite the fact that high seas are the only domain in which India can checkmate China given its natural geographic advantages. China already has the world’s largest navy with 350 warships, including 50 conventional and 10 nuclear submarines.
• India’s Delay in Modernisation: For example, delay in signing the contract for P-75.
• Shortfall in Indian Navy Essentials: There are other significant shortfalls of the Indian Navy including essentials capacities such as “Advanced Towed Array Sonars (ATAS) to detect enemy submarines, heavyweight torpedoes to neutralize them, and varied air defense systems, all of which are critical not only to their survivability, but also their overall offensive capability.
• Deal Cancellation: India cancelled a deal for the heavy-weight Black Shark torpedoes, built by the Finmecannica subsidiary WASS, as a result of an unrelated corruption scandal that involved another subsidiary of Finmecannica, Augusta-Westland.
• Slow Development of AIP System: The Air Independent Propulsion (AIP) system allows submarines to stay underwater for longer periods of time without being detected. However, the development of the indigenous AIP system by the Defence Research and Development Organization (DRDO) has been delayed.
• Government’s Less Attention to Navy: Much of the Indian budget is focused on the Army, with the air force being a distant second and the navy a poor third. And with naval capability building proving time-consuming and capital-intensive, that leaves India stuck with a continued slow pace of development of its naval capabilities relative to other actors, even as competitors such as China forge ahead more quickly.