A landmark defence dimension of German Chancellor Friedrich Merz's January 12, 2026 India visit was the signing of a Joint Declaration of Intent (JDoI) to develop a Defence Industrial Cooperation Roadmap — a framework for long-term industry-level collaboration including co-development, co-production, and technology transfer for defence platforms and equipment. The most significant element was an agreement-in-principle for submarine co-production: India and Germany would jointly build submarines, combining German expertise in advanced underwater naval systems with India's growing domestic defence industrial base. This aligns with India's strategic goal of indigenising defence manufacturing under the 'Aatmanirbhar Bharat' initiative and Defence Acquisition Procedure (DAP) 2020. Germany's defence industry — particularly companies like ThyssenKrupp Marine Systems (TKMS), which builds Type 212 and Type 214 submarines — has long been eyed as a potential partner for India's Project 75I programme (six advanced submarines). The JDoI also covers co-development of other defence equipment, technology partnerships, and supply-chain integration. Germany, which has been working to reduce dependence on Russia for defence supplies since the 2022 Ukraine war, sees India as an important partner in diversifying its defence-industrial ecosystem. For India, the agreement opens a new European strategic partnership track complementing existing US, France, Israel, and Russia defence ties. The roadmap is expected to produce concrete co-production projects within 18–24 months.