An opening to India's secretive INS Varsha underground submarine base

India is constructing a submarine base in the Bay of Bengal that when completed will provide a sanctuary for its sea-based nuclear deterrent against Pakistan and China. INS Varsha will protect India’s submarine assets underground

Asia Times reported that India’s ambitious Project Varsha, a sprawling 1,680-acre naval base, is rapidly taking shape on the Eastern Coast at Rambilli. Recent satellite images indicate a rapid expansion, suggesting the project is on track for completion within its designated timeframe.

Project Varsha is a strategic naval base designed to house a fleet of over 12 nuclear-powered ballistic missile submarines (SSBNs). Its most striking feature is an extensive underground complex, revealed by satellite imagery, which includes tunnels likely intended as submarine pens.

The base’s underground sanctuary promises to protect India’s SSBNs from aerial threats and prying eyes while also providing essential support facilities for nuclear engineering. Above ground, the construction of piers suggests the capability to accommodate a variety of surface vessels, enhancing the base’s operational flexibility.

Project Varsha’s location offers a strategic advantage by positioning the Indian Navy closer to the critical shipping lanes of the Indo-Pacific. This proximity allows for a swift response to regional threats and facilitates collaboration with the Bhabha Atomic Research Center (BARC), India’s nuclear establishment.

Project Varsha is designed to enhance significantly India’s naval deterrence, allowing the deployment of nuclear-armed submarines from a secure, underground base. This signals India’s commitment to maintaining a formidable presence in the Indian Ocean region, ensuring the nation’s security and bolstering its position as a major maritime power.

INS Varsha will protect India’s submarine assets underground. Image: X Screengrab

India aims to have four SSBNs to deal with the dual threat that Pakistan and China pose. Currently, India has one active SSBN, the INS Arihant, which is armed with 12 K-15 submarine-launched ballistic missiles (SLBM) with a relatively short range of 700 kilometers. India plans to commission its second SSBN, the INS Arighat, by the end of this year, almost seven years after its launch.

India’s third SSBN, codenamed S4, is under construction and is believed to be larger than its predecessors. Satellite imagery has shown that S4 may carry twice the SLBMs of INS Arihant and INS Arighat. It could have 24 K-15 SLBMs or 8 K-4 SLBMs with a range of 3,500 kilometers.

India will likely complete the S4 this year and then schedule sea trials. Following that, India’s fourth SSBN will likely be based on the S4, with varying improvements over its predecessor.

However, Yogesh Joshi points out in a January 2019 War on The Rocks article that unless India fields SLBMs with intercontinental range, its sea-based nuclear deterrent will lack credibility versus Pakistan and China.

In line with that assessment, Hans Kristensen and Matt Korda note in a July 2022 Bulletin of the Atomic Scientists article that the K-15 SLBM’s range would limit it to targets in southern Pakistan, and its SSBNs would not be able to target all of China unless they sail through the Malacca Strait.

However, India is already developing the K-5 SLBM with a range of 5,000 kilometers, although the project is highly classified due to strategic and security considerations.

India faces a dual nuclear threat from Pakistan and China, with the latter increasingly finding convergence in a “threshold alliance” with Pakistan, a relationship that is less than a formal alliance but more than general defense cooperation.

In May 2024, Asia Times reported that Pakistan launched its first China-built Hangor-class submarine, an export variant of the Type 039B Yuan-class SSK. In April 2015, Pakistan signed a contract with China for eight submarines, with four built in China and the remainder in Pakistan.

Pakistan will acquire significant deep strike capability if it arms its Hangor-class submarines with nuclear-tipped Babur-3 submarine-launched cruise missiles (SLCM), which have a 450-kilometer range.

The use of sea-based tactical nuclear weapons by Pakistan would help counter India’s conventional military strength while also keeping its nuclear weapons hidden from potential preemptive strikes. Additionally, it would enable Pakistan to maintain a credible second-strike capability.

While China has been a primary enabler of Pakistan’s nuclear weapons program, it may opt to maintain a safe distance from Pakistan’s ambitions considering the threat of nuclear proliferation.

Via the infamous A Q Khan nuclear proliferation network, Chinese nuclear weapons designs and missile technology have made their way from Pakistan to Libya, North Korea, Iran and possibly others, which is not in China’s interest as more nuclear-armed players in Asia and elsewhere could disrupt the global balance of power.

Iskander Rehman notes in a March 2015 Carnegie Endowment for Regional Peace report that Project Varsha would enable India to use the Bay of Bengal as an SSBN bastion against Pakistan and China, with its deep waters providing better cover than the congested waters of the Arabian Sea.

Rehman notes that Project Varsha’s submarine base will allow India’s SSBNs to slip into the Bay of Bengal without being detected by satellites and aircraft.

In an Indian SSBN bastion strategy, the Bay of Bengal will be protected by surface assets such as India’s upcoming third aircraft carrier and its escorts, providing a secure area where India could launch SLBMs undetected at Pakistani and Chinese targets.

While Rehman notes that it is unlikely for China’s SSBNs to move into the Bay of Bengal, as they would have to traverse the congested Malacca Strait to do so, he says that India-China nuclear tensions will most likely stem from penetrations of each other’s nuclear bastions with conventional assets.

In April 2024, The Hindustan Times reported that China had deployed three spy ships in the Indian Ocean to map the region for future submarine operations and naval deployments.

The Hindustan Times report said that one of those ships, the Xiang Yang Hong 01, conducted trials of a high-endurance autonomous underwater vessel. The report says the vessel can stay at depths of up to nearly 12 kilometers for three months, mapping the seafloor and collecting oceanographic data for submarine operations.

India’s increasing naval presence in the South China Sea may threaten China’s SSBNs, as China aims to transform the contested maritime area into a bastion for its SSBN fleet.

China’s new JL-3 SLBM’s range of 7,200 kilometers will allow it to use the South China Sea as a bastion for its SSBN fleet. This capability will eliminate the need for its SSBNs to cross chokepoints such as the Miyako Strait and Bashi Channel to reach the open waters of the Pacific and bring the mainland US into SLBM range.

Last month, Newsweek reported that a flotilla of three Indian warships, consisting of the destroyer INS Delhi, the anti-submarine corvette INS Kiltan, and fleet tanker INS Shakti, visited Manila as part of an operational deployment to Southeast Asia, which included port calls in Malaysia and Singapore.