The clean energy transition is complicated by material constraints that threaten national security. Idealized proposals for a rapid decarbonization via a greatly accelerated diffusion of solar, wind, battery and other technologies entails massive amounts of critical raw materials (CRM). These CRM include copper, aluminum, cobalt, lithium, graphite, rare earths, and other minerals and metals. In the international debate, CRM are also referred to as “critical minerals,” “critical strategic minerals,” “battery minerals,” “energy transition metals,” and various other terms. The International Energy Agency (IEA) aggressively supports decarbonization, but also warns that zero-carbon scenarios imply that the energy sector's overall demand for CRM could sextuple by 2040. Japan aims for net-zero greenhouse gas (GHG) emissions by 2050, and India's net-zero target is two decades later. But like all countries, their CRM supply chains are at present unable to satisfy ambitious goals for deploying solar, wind, battery storage, power transmission, and green hydrogen. Multilateral cooperation is imperative to address the growing challenges of CRM, especially their price volatility, security of supply, and Environment, Social, and Governance (ESG) issues. Building a sustainable and diversified global supply chain is crucial to building security in clean energy. One step in this direction was seen in September 2021, when Japan, India and other members of the Quadrilateral Security Dialogue, or QUAD, signed an agreement for cooperation in procuring rare earths. This paper discusses potential additional cooperation between India and Japan, for bolstering both countries' CRM supply security.