India's naval infrastructure is undergoing a transformative expansion, marked by the near-completion of INS Varsha, a secretive underground submarine base in Andhra Pradesh, and the simultaneous modernisation of the Karwar Naval Base under Project Seabird on the western coast.

The first phase of the Rambilli naval base under Project Varsha is almost complete. After commissioning in 2026, it can be expanded and upgraded in phases. This will enable the submarine vessels to quietly slip into the Bay of Bengal undetected by Chinese or Western spy satellites.

These developments, part of India’s broader strategy to counterbalance China’s growing influence in the Indian Ocean Region (IOR) and address emerging threats near the Siliguri Corridor, reflect a calculated shift toward securing undersea nuclear deterrence and enhancing maritime operational flexibility.

The commissioning of INS Aridhaman, India’s third nuclear-powered ballistic missile submarine (SSBN), and reports of a potential Chinese-backed airbase in Bangladesh’s Lalmonirhat district further underscore the geopolitical urgency driving these projects. This report examines the technical, strategic, and diplomatic dimensions of India’s naval modernisation, situating it within the context of regional power dynamics and nuclear deterrence imperatives.

Project Varsha: India’s Subterranean Submarine Citadel

Located in Rambilli, approximately 50 km south of Visakhapatnam, INS Varsha occupies a strategically vital position along India’s eastern coastline. The base’s proximity to the confluence of the Sarada and Varaha rivers provides natural topographical advantages, including deep-water access that enables submarines to submerge immediately upon departure, evading detection by satellite surveillance. This feature is critical for India’s Arihant-class SSBNs, which require stealth to conduct deterrence patrols in the Bay of Bengal and beyond toward the Malacca Strait—a choke-point dominating access to the South China Sea.

Underground Infrastructure And Stealth Capabilities

The facility’s defining characteristic is its network of underground pens and tunnels, carved into the Eastern Ghats hills, designed to shield submarines from aerial attacks and electronic reconnaissance. Comparable to China’s Hainan Island nuclear submarine base, these reinforced concrete structures accommodate up to 12 SSBNs and include dedicated support infrastructure managed by the Bhabha Atomic Research Centre (BARC). Phase-I construction, initiated in 2011 with an initial allocation of ₹160 crore (US$38 million in 2023), focused on civil works and a Very Low Frequency (VLF) communication system essential for secure submarine communication. Phase-II, involving the diversion of 670 hectares of forest land for a technical command centre, is slated for completion by 2025–2026.

Technological And Environmental Challenges

Delays in Project Varsha’s timeline have stemmed from the complexity of constructing subterranean dry docks capable of housing 7,000-tonne submarines and mitigating environmental concerns in the ecologically sensitive Rambilli region. The Indian Navy has sought foreign technical assistance, particularly for nuclear safety protocols and reactor maintenance systems, highlighting the project’s reliance on international expertise despite its indigenous design.

INS Aridhaman And The Maturation of India’s Nuclear Triad: Technology Advancements In The Arihant-Class

INS Aridhaman, commissioned in February 2025, represents a significant leap in India’s SSBN capabilities. With a displacement of 7,000 tonnes—1,500 tonnes heavier than its predecessors INS Arihant and INS Arighat—the submarine features an upgraded CLWR-B1 compact light-water reactor generating 83 MW, enabling submerged speeds of 24 knots (44 km/h). Its enhanced missile silos can carry 12–16 K-4 SLBMs (Submarine-Launched Ballistic Missiles) with a range of 3,500 km, tripling the strike range of earlier K-15 missiles. This expansion ensures that India’s SSBNs can target critical locations across southern China and the western Pacific from positions within the Bay of Bengal.

The Advanced Technology Vessel (ATV) Program

The ₹90,000 crore ATV project underpins India’s ambition to operationalise a fleet of six SSBNs and six nuclear-powered attack submarines (SSNs). The fourth SSBN, currently under construction at Visakhapatnam’s Ship Building Centre, will displace 13,500 tonnes and integrate a 190 MW pressurised water reactor, marking a generational shift in reactor efficiency and stealth. Concurrently, the Cabinet Committee on Security has approved ₹40,000 crore for two 9,800-tonne SSNs, optimised for anti-ship and intelligence-gathering missions in contested waters.

Project Seabird: Securing The Western Maritime Frontier: Infrastructure Expansion at Karwar Naval Base

While Project Varsha fortifies India’s eastern seaboard, Project Seabird aims to alleviate congestion at Mumbai Harbour by establishing a mega-naval base at Karwar, Karnataka. Phase-IIA, inaugurated in April 2025, adds 32 warship berths, a 3,000-foot runway, and covered dry docks for submarine maintenance. The base’s dual-use air station and ordnance handling facilities provide integrated support for carrier battle groups, a capability absent in older naval installations.

Strategic Implications For Pakistan-Centric Operations

Karwar’s geographical position—1,000 km south of Mumbai—reduces vulnerability to Pakistani missile strikes while offering rapid deployment access to the Arabian Sea and Persian Gulf. With Phase-IIB poised to expand capacity to 50 warships and 40 auxiliary vessels by 2030, Karwar will serve as the primary hub for India’s western fleet, including aircraft carriers like INS Vikrant and Scorpène-class submarines.

The Bangladesh-China Nexus: Threats to the Siliguri Corridor: Lalmonirhat Airbase And Its Strategic Risks

Reports of a proposed Chinese-backed airbase in Bangladesh’s Lalmonirhat district, 40 km from India’s Siliguri Corridor (Chicken’s Neck), have intensified regional tensions. The 700-acre facility, purportedly capable of hosting 70 fighter jets, would enable Chinese PLAAF deployments within minutes of India’s northeastern supply routes. Although Bangladesh has denied formal agreements, high-level discussions during Chief Adviser Muhammad Yunus’s March 2025 visit to Beijing suggest growing Sino-Bangladeshi defence collaboration.

Diplomatic Shifts And Pakistani Engagement

Concurrent with airbase rumours, Pakistan’s Foreign Minister Ishaq Dar and Foreign Secretary Amna Baloch plan visits to Dhaka in April 2025—the first since 2012—to finalise bilateral agreements. This diplomatic thaw, coupled with Bangladesh’s abstention from UN resolutions critical of China, signals a potential reorientation toward Beijing and Islamabad, complicating India’s regional calculus.

Geopolitical Synthesis: India’s Maritime Doctrine In The Indo-Pacific: Countering Chinese Expansionism

India’s dual-base strategy (Varsha and Seabird) mirrors China’s “String of Pearls” doctrine, which seeks to establish naval footholds across the IOR. By securing undersea second-strike capabilities and dispersing fleet assets across both coasts, India aims to deter Chinese incursions into the Andaman Sea and diminish PLAN (People’s Liberation Army Navy) dominance near the Malacca Strait.

Strengthening The Nuclear Triad

The Arihant-class SSBNs, supported by INS Varsha’s stealth infrastructure, complete India’s nuclear triad, ensuring survivable retaliation capabilities. With four SSBNs projected by 2030, India’s sea-based deterrence will cover 95% of China and 70% of Pakistan, recalibrating regional power dynamics.

Integrated Theatre Command Considerations

The Eastern Naval Command’s operational control over INS Varsha, in coordination with the Strategic Forces Command, underscores India’s move toward integrated theatre commands—a reform initiative aimed at streamlining joint operations across military branches.

Conclusion: Securing The Indo-Pacific Balance

India’s naval modernisation, epitomised by INS Varsha and Project Seabird, reflects a nuanced response to multifaceted threats: Chinese submarine deployments in the IOR, Pakistan’s naval partnerships with Turkey and China, and emerging airpower challenges near the Siliguri Corridor. By prioritising undersea stealth, nuclear triad readiness, and infrastructure redundancy, India seeks to assert itself as a net security provider in the Indo-Pacific while safeguarding its existential interests. However, sustained success will depend on overcoming bureaucratic delays, environmental pushback, and the need for international technical partnerships. As regional alliances shift, India’s ability to leverage these naval assets for diplomatic deterrence—rather than mere confrontation—will define its role in the 21st-century maritime order.

Based On A ET News Report