India and Japan Sign Landmark Defence Industrial Pact Covering Submarines, Radars and Munitions

India and Japan signed their most far-reaching defence industrial agreement to date on May 11, 2026, during Prime Minister Narendra Modi's working visit to Tokyo. The package, formally titled the India-Japan Defence Industrial Cooperation Framework, covers joint development and production across three priority areas: conventional submarines, ground-based air-defence radars, and select categories of guided munitions. It is the first time Japan has committed to co-production of major undersea platforms with a partner outside the United States.

Three Programmes, One Framework

The headline element is a memorandum of understanding between Mitsubishi Heavy Industries, Kawasaki Heavy Industries and India's Mazagon Dock Shipbuilders to jointly produce a derivative of Japan's Taigei-class diesel-electric submarine. India will build six hulls at Mumbai under technology transfer, with the first launch targeted for 2032. The boats will use lithium-ion batteries and air-independent propulsion modules supplied initially from Kobe, with Indian content reaching 60 percent by the fourth hull.

The second element is co-production of NEC's air-defence radar architecture, to be integrated with Bharat Electronics' fire-control systems for the Indian Air Force. The third covers anti-ship and surface-to-air missile components, with Japanese precision optics and Indian solid-rocket motor manufacturing matched in a way that neither country has previously attempted with outside partners.

Why the Two Capitals Moved Now

Three factors converged. China's South China Sea posture has hardened through 2025 and into 2026, with persistent grey-zone activity around Scarborough Shoal and the Senkaku Islands. Tokyo's revised National Security Strategy explicitly identifies India as a top-tier defence-industrial partner. And New Delhi's frustration with the pace of French Scorpene-class follow-on negotiations has pushed it toward a faster, technology-richer alternative.

Japanese officials told reporters that the submarine agreement required cabinet-level political cover, since exports of major platforms remain politically sensitive in Tokyo even after the 2023 revisions to the Three Principles on Defence Equipment Transfer. The pact treats India as a co-developer rather than an end-customer, a legal distinction that mattered domestically in Japan.

Programme Components

• Six Taigei-derivative submarines built at Mazagon Dock
• Air-defence radar joint production between NEC and BEL
• Guided munitions component cooperation with shared optics and motors
• Joint MRO facility in Visakhapatnam for the new submarine class
• Defence-industrial workforce exchange of 400 engineers across both countries

Regional Reactions

China's Ministry of Foreign Affairs called the agreement destabilising and warned both capitals against forming exclusionary blocs in Asia. The reaction in Washington was warmer; the Pentagon issued a statement welcoming the deepening of trilateral US-Japan-India defence ties under the Quad framework. Australia and the Philippines, both Quad-adjacent partners, signalled they would seek consultation on potential interoperability with their own submarine and radar programmes.

Within ASEAN, the response was measured. Vietnam, which operates Russian Kilo-class submarines, has been quietly studying alternative sources, and Hanoi diplomats privately suggested they would watch the India-Japan programme as a potential second-source pathway. Singapore, Indonesia and Malaysia stayed publicly neutral.

The Industrial Math

Programme cost is estimated at 4.2 trillion yen across all three components, of which roughly 60 percent will be borne by India and 40 percent by Japan. Mitsubishi and Kawasaki will receive lump-sum technology-transfer payments worth approximately 380 billion yen between 2026 and 2032. The Indian government has indicated the submarine programme alone will create 12,000 direct jobs at Mumbai and an additional 18,000 across the supplier base, with particular emphasis on small and medium enterprises in Maharashtra and Gujarat.

What Could Go Wrong

Three risks loom. The first is the well-documented pattern of Indian shipbuilding delays at Mazagon Dock, where the previous Scorpene programme ran roughly six years behind its original schedule. The second is political turnover; a future Japanese cabinet could reinterpret the export framework, and a future Indian government could revisit the supplier mix. The third is technology security, since Indian and Japanese cyber-defences against industrial espionage have historically operated on different standards.

To address the third risk, both governments have committed to a joint counter-intelligence working group, with monthly reporting to a designated minister in each capital.

Broader Strategic Context

The pact lands at a moment when Asian defence procurement is undergoing one of its largest shifts in three decades. South Korea has emerged as a major exporter of self-propelled artillery and tanks to Poland and the Middle East. Japan has lifted multiple export restrictions and is now selling air-defence components to the Philippines. India's Tejas fighter has secured small export orders in Africa and South America. The region is no longer a pure importer of platforms designed elsewhere; it is increasingly a co-developer and exporter in its own right.

The India-Japan submarine programme sits at the apex of that trend. If it delivers on schedule, it positions both countries as credible suppliers of major undersea platforms to a third group of regional buyers, including Vietnam, Indonesia and potentially the Philippines, all of which have signalled long-term submarine ambitions.

What to Watch in the Next Six Months

Three milestones matter most. The finalisation of the technology-transfer pricing schedule, due by September. The selection of Japanese ancillary suppliers for the Mazagon hull line, expected by late summer. And, most importantly, the first joint design review in November, which will signal whether the programme can hold its 2032 launch date or whether the familiar drift toward delay has already begun. If the design review converges cleanly, India and Japan will have set a new template for Asian defence-industrial cooperation. If it slips, the pact becomes another well-intentioned framework still searching for delivery.