The recent US submarine action against an Iranian vessel in the Indian Ocean, perhaps the first time a US submarine has conducted a naval strike since World War II, has brought underwater striking capabilities and underwater warfare into the spotlight. The US’s naval strike in India’s core maritime sphere highlights the need to focus on underwater striking capabilities, especially in the context of Operation Sindoor’s success and India’s efforts to sharpen its deterrence and counter-striking capabilities.
During the Cold War, the US Navy and the CIA conducted an audacious underwater operation that almost changed the balance of maritime power between the two archrivals. A highly classified operation codenamed Operation Ivy Bells. The operation involved tapping into a Soviet underwater military communications cable in the Sea of Okhotsk, a heavily guarded area of the Soviet Far East.
The Action
A specially modified submarine, USS Halibut, entered Soviet waters, and its divers installed a large, sophisticated wiretapping device around the cable. The device recorded Soviet communications. For almost a decade, the US collected invaluable, unencrypted intelligence on Soviet naval operations, including submarine movements and missile tests, until it was compromised in 1981 when the US’s National Security Agency (NSA) sold information to the KGB. As India and Germany prepare for talks to seal its largest-ever single defence contract, valued at almost 8 billion dollars, to upgrade its Project 75I and build six advanced conventional submarines, it must also realise the importance of underwater warfare in the coming time.
The Underwater Tactics: New Reality
Beyond surface maritime operations, underwater or subsurface operations are growing beyond naval surveillance. Underwater warfare tactics are also emerging as strong means of deterrence through denial and punishment options akin to those of the Air Force and Army. There are three key drivers or threats that press upon the need to develop strong underwater warfare capabilities.
First– The China Threat: China is expanding its underwater warfare capabilities, where it is developing next-generation submarines like the Type 096 SSBN, which is expected to be significantly quieter and harder to detect. A US government report anticipates that China will grow its submarine fleet by 65 by the end of 2025 and by 80 by 2030, making It the world’s largest submarine power, surpassing both the US and Russia.
Second: Maritime Geopolitics: The Indo-Pacific region remains underprepared to counter China’s expanding naval power, particularly its underwater warfare capabilities, which could enable area denial—deterring opponents through denial—against the US Navy and other naval forces, thereby establishing China’s maritime dominance in the area. This threat also reverberates in the Indian Ocean against the Indian Navy in the coming years. Such a scenario is likely to be exploited as geopolitical leverage to negotiate and further diminish the strategic and geopolitical influence of the US and India in and around the Indian Ocean.
Third: Energy and Infrastructural Security: One major security concern is that the covert domain could become highly vulnerable to underwater warfare tactics. The undersea cables—95% of all global internet data, financial transactions, and communications—run through a network of undersea fibre-optic cables, and a single strike or cut by an Unmanned Underwater Vehicle or a submarine could cripple a nation’s strategic communications and economic security. Similarly, underwater gas pipeline lines are also under threat. The Nord Stream sabotage in 2022 is a clear example in which naval experts have argued that either UUVs or naval bottom mines caused the damage to the pipelines.
While Intelligence, Surveillance, and Reconnaissance (ISR) operations remain the primary set of underwater warfare tactics, there should be no complacency in believing that the evolving dynamics of subsurface warfare pose more serious and greater security challenges that large ships or surface-level maritime power will not be able to counter effectively.
Serious Situation With the Indian Navy
In the traditional maritime domain, the Indian Navy is making good progress, with plans to expand the fleet by inducting 175-200 ships by 2035, while increasing capacity for modernisation and indigenisation. However, the situation is grim when it comes to the Navy’s unconventional or underwater warfare capabilities. The Indian Navy’s submarine fleet is ageing, comprising Russian-origin Kilo-class (Sindhughosh-class) and German-origin HDW (Shishumar-class) submarines; the induction of the Scorpène-class (Kalvari) submarines has been slow. The status of Nuclear attack Submarine (SSN) is also worrisome; the Navy does not have any nuclear-powered attack submarine in active service. The leased Russian SSN, INS Chakra-II, was decommissioned in 2021.
Nuclear attack submarines (SSNs) are crucial for hunting enemy submarines, targeting surface ships, and in maritime security operations to protect their own vessels and aircraft carriers. The crucial aspect of SSN submarines is their virtually unlimited underwater endurance and range; they can stay submerged for months, allowing them to conduct both underwater ISR and offensive operations without surfacing for air or refuelling.
Navy’s one of its ambitious projects—Project-75I—which aims to build six advanced conventional submarines with Air Independent Propulsion (AIP) for long underwater endurance, has faced extensive delays as the navy struggles to maintain its dwindling submarines. The Project 75I holds the key to modernising and reviving them. Originally conceived in 1997, the Project 75I is still in multiple negotiating phases, stretching the delay to over two decades.
Drying Up Mines
Another key aspect of underwater tactics is mine warfare, where naval bottom mines and minesweepers play a vital role in providing strong, long-term deterrence and area denial operations by creating blockades and choke points in maritime regions. The mine counter vessels can oppose maritime denial operations and are effective in mine warfare. The current status of mine counter vessels in the Indian navy is that Pondichéry-class minesweepers are gradually becoming obsolete.
The Threat Is Real
The threat of underwater warfare is real and to some extent it has been realised by Naval top brass the recent statement of Vice-admiral K Swaminathan, who leads the Western Naval Command headquartered in Mumbai, said last week that “China was not only becoming more assertive in the South China Sea but also in the Indian Ocean region” He further added “China will continue to be an enduring challenge,”
While the Navy continues to develop its ambitious indigenous program, it also makes slight adjustments to its naval fighting doctrine. The current doctrine emphasizes applying naval power across various conflicts, but given the unconventional nature of modern warfare, the Indian Navy should adopt a more aggressive stance, similar to China. China follows the Near Seas Defence and Far Seas Protection strategy, which gives its navy an assertive posture. Strategic use of naval firepower can support maneuvering and maritime defensive operations. However, to pursue an offensive strategy effectively, the Indian Navy must consider asserting control, employing grey zone tactics, and conducting covert maritime actions—imposing deterrence through denial and punishment, which are key elements of underwater warfare. Overall, the Indian Navy should focus more on assertiveness than mere application, deploying offensive and assertive naval power and capabilities as outlined by renowned naval strategist Alfred Thayer Mahan—aiming to achieve command of the sea through a strong naval offensive and battle fleet strategy.
As the Indian Navy waits for its opportunity to shift into action mode after 1971, especially during and after Operation Sindoor, it must prepare for a wide range of unconventional naval warfare to demonstrate its lethality and decisive power in South Asia, thereby sending a strategic message to China.
