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International Relations April 29, 2026 6 min read Daily brief · #6 of 57

India–Sri Lanka maritime ties strengthened through IN–SLN DIVEX 2026

The fourth edition of the India-Sri Lanka bilateral diving exercise, IN-SLN DIVEX 2026, was conducted in Colombo from 21 to 28 April 2026, with the Indian Na...

GS2 (International Relations India and its Neighbourhood Bilateral Groupings Internal Security)

What Happened

  • The fourth edition of the India-Sri Lanka bilateral diving exercise, IN-SLN DIVEX 2026, was conducted in Colombo from 21 to 28 April 2026, with the Indian Navy deploying its specialised vessel INS Nireekshak — built for deep-sea diving and submarine rescue operations.
  • Divers from both navies executed mixed-gas deep-sea dives beyond 55 metres over World War-era wrecks (SS Worcester and SS Perseus) off Colombo, marking a significant advance in joint underwater search, rescue, and salvage capability.
  • The exercise extended beyond combat diving to include humanitarian dimensions: two BHISM (Bharat Health Initiative for Sahyog, Hita and Maitri) cubes were handed over under India's Aarogya Maitri initiative, alongside beach clean-up drives and sports activities — underscoring the whole-of-partnership approach India employs in the Indian Ocean neighbourhood.

Static Topic Bridges

India-Sri Lanka Bilateral Relations: History and Structural Issues

India and Sri Lanka share one of South Asia's oldest and most complex bilateral relationships, spanning civilisational ties, post-independence cooperation, the Tamil ethnic conflict, and recurring maritime disputes. The bilateral framework has matured significantly since the end of Sri Lanka's civil war in 2009.

  • The 1974 Maritime Boundary Agreement (signed between Prime Ministers Indira Gandhi and Sirimavo Bandaranaike) ceded the 285-acre uninhabited island of Katchatheevu in the Palk Strait to Sri Lanka, with a clause allowing Indian fishermen and pilgrims to visit without travel documents — but without explicit fishing rights in surrounding waters.
  • Over 500 Indian fishermen were arrested by Sri Lankan authorities in 2024 alone for alleged fishing violations in Sri Lankan waters, making the fisheries dispute a persistent irritant in bilateral ties.
  • The Economic and Technology Cooperation Agreement (ETCA) negotiations resumed in October 2023, aiming for deeper trade and investment integration between the two countries.
  • A landmark 5-year Defence Memorandum of Understanding (MoU) was signed in 2025, structuring joint exercises including SLINEX (naval), MITRA SHAKTI (army), and DIVEX (diving), along with maritime surveillance and defence technology cooperation.
  • Sri Lanka's strategic location — at the apex of the triangular Indian Ocean sea lanes between the Strait of Malacca, the Strait of Hormuz, and the Cape of Good Hope — gives it outsized importance for Indian Ocean security.

Connection to this news: IN-SLN DIVEX is a practical manifestation of the 2025 Defence MoU, building underwater search-and-rescue interoperability that serves both countries' interests in the heavily trafficked sea lanes around Sri Lanka.

SAGAR Doctrine and Its Evolution to MAHASAGAR

SAGAR (Security and Growth for All in the Region) was articulated as India's maritime vision by the Prime Minister in March 2015 during a visit to Mauritius. It established India's intent to act as a net security provider in the Indian Ocean Region (IOR), offering defence cooperation, intelligence sharing, and humanitarian assistance to smaller island states and littoral neighbours.

  • Five pillars of SAGAR: (1) Security cooperation — bilateral and multilateral maritime security; (2) Trade and economic integration — blue economy development; (3) Capacity building and disaster management — maritime infrastructure and HADR; (4) Sustainable development — marine resource management; (5) Connectivity and infrastructure — ports, naval bases, digital services.
  • SAGAR explicitly positions India as the preferred security partner for Sri Lanka, Maldives, Seychelles, Mauritius, and Bangladesh — countering Chinese naval expansion in the IOR.
  • In March 2025, the same venue (Mauritius) saw the announcement of MAHASAGAR (Mutual and Holistic Advancement for Security and Growth Across Regions) — an evolution of SAGAR with a more globally oriented and structured mandate extending beyond the IOR into the broader Indo-Pacific.
  • DIVEX, along with SLINEX, the Humanitarian Assistance and Disaster Relief (HADR) exercises, and the Aarogya Maitri medical diplomacy, are operational expressions of the SAGAR/MAHASAGAR framework.

Connection to this news: IN-SLN DIVEX 2026 is a direct operational application of the SAGAR/MAHASAGAR doctrine — building interoperability in undersea salvage and rescue, a capability critical for both maritime security and disaster response in the IOR.

Joint Military Exercises — Significance and India's Neighbourhood First Policy

India's Neighbourhood First Policy, articulated in 2014, prioritises deepening political, economic, and security cooperation with immediate neighbours — Bangladesh, Bhutan, Maldives, Nepal, Pakistan, Sri Lanka, and Afghanistan. Joint military exercises are a primary instrument of operationalising this policy at the defence-security level.

  • Joint exercises serve three key UPSC-relevant functions: (1) Interoperability — aligned procedures, communications, and tactics for joint operations; (2) Capacity building — transferring skills and equipment knowledge to smaller navies; (3) Signalling — demonstrating the depth of the bilateral defence relationship to third parties (notably China).
  • India's key bilateral exercises in the maritime domain include: SLINEX (India-Sri Lanka; surface and sub-surface naval exercises), DOSTI (India-Sri Lanka-Maldives; coast guard), MITRA SHAKTI (India-Sri Lanka army), and DIVEX (India-Sri Lanka specialised diving).
  • The exercise also served humanitarian purposes: the BHISM cube handover under Aarogya Maitri — India's medical diplomacy initiative — signals that defence cooperation includes disaster medical preparedness, not just combat readiness.
  • Sri Lanka has received from India: Line of Credit for infrastructure, Unified Payments Interface (UPI) integration, supply of petroleum products during the 2022 economic crisis, and naval vessels for maritime surveillance.

Connection to this news: DIVEX 2026 exemplifies how India uses specialised capability-building exercises to deepen defence partnerships in its neighbourhood — the underwater salvage focus addresses a real operational gap for Sri Lanka's relatively limited submarine rescue capacity.

Indian Ocean Security Architecture: IORA and Colombo Security Conclave

India participates in two key multilateral frameworks for Indian Ocean security beyond bilateral exercises.

  • IORA (Indian Ocean Rim Association): 23-member intergovernmental organisation established in 1997, headquartered in Ebene, Mauritius. Mandate covers trade, investment, maritime safety, blue economy, and people-to-people cooperation. Members include India, Sri Lanka, Australia, Indonesia, South Africa, UAE, and others. It is a trade-and-cooperation forum rather than a defence alliance.
  • Colombo Security Conclave (CSC): Originally a trilateral India-Sri Lanka-Maldives dialogue launched in 2011 on maritime security; evolved into a 6-member grouping with Bangladesh, Mauritius, and Seychelles as additional members. Its five pillars are: maritime safety & security; counter-terrorism & radicalisation; combating trafficking & transnational organised crime; cybersecurity & critical infrastructure protection; and HADR.
  • CSC operates at the National Security Adviser (NSA) level with an interim secretariat in Colombo.
  • In April 2026, the External Affairs Minister announced the upgrading of the CSC to a more structured and outward-looking regional security framework — a significant institutional evolution.

Connection to this news: DIVEX strengthens the bilateral military foundation upon which multilateral frameworks like the CSC rest — India-Sri Lanka deep interoperability is a prerequisite for effective joint response to the maritime security threats the CSC is designed to address.

Key Facts & Data

  • IN-SLN DIVEX 2026: 4th edition; conducted 21–28 April 2026, Colombo
  • Indian vessel deployed: INS Nireekshak (deep-sea diving and submarine rescue ship)
  • Dive depth achieved: beyond 55 metres using mixed-gas techniques
  • Katchatheevu ceded to Sri Lanka: 1974 agreement (285 acres, Palk Strait)
  • Indian fishermen arrested by Sri Lanka in 2024: over 500
  • SAGAR articulated: March 2015 (Mauritius); evolved to MAHASAGAR: March 2025 (Mauritius)
  • Colombo Security Conclave launched: 2011 (trilateral); current members: 6 (India, Sri Lanka, Maldives, Bangladesh, Mauritius, Seychelles)
  • CSC upgrade announced: April 2026
  • IORA members: 23; established: 1997
  • 5-year India-Sri Lanka Defence MoU: signed 2025
On this page
  1. What Happened
  2. Static Topic Bridges
  3. India-Sri Lanka Bilateral Relations: History and Structural Issues
  4. SAGAR Doctrine and Its Evolution to MAHASAGAR
  5. Joint Military Exercises — Significance and India's Neighbourhood First Policy
  6. Indian Ocean Security Architecture: IORA and Colombo Security Conclave
  7. Key Facts & Data
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