US-Japan HPM PA

Intelligence Summary: US-Japan HPM Partners Agreement

Node Identity: The US-Japan High-Power Microwave (HPM) Project Arrangement is a bilateral defense cooperation agreement signed on July 15, 2024, between Japan's ATLA (Acquisition, Technology & Logistics Agency) and the US Department of Defense. The agreement establishes a framework for joint research, testing, and data sharing on directed energy HPM systems through fiscal year 2030, with joint tests conducted at US test centers targeting air and maritime defense applications.

Strategic Relevance to FRC/Plasma Weapons Context: The US-Japan HPM PA is strategically significant as the most concrete bilateral mechanism for plasma-relevant weapons technology sharing between the US and a Pacific ally. HPM weapons operate by generating intense electromagnetic pulses that disable electronic systems — the underlying physics involves microwave-plasma interactions, relativistic electron beam generation, and electromagnetic propagation through ionized media. Japan's 2022 Defense Buildup Program designated microwave technology as a priority for drone interception, and ATLA has been researching HPM technology since 2014 with a ~$63M program (FY2022-FY2026) developing a phased-array HPM radiation weapon. The bilateral agreement enables Japan to test HPM systems at US facilities with superior test infrastructure, while providing the US with access to Japanese HPM source technology and effects data. This arrangement complements the Five Eyes TTCP framework and AUKUS Pillar II EW workstream, extending plasma-relevant DEW cooperation into the Indo-Pacific.

Technical Focus / Capabilities: The Project Arrangement covers: (1) joint testing of HPM systems against electronic devices at US test centers; (2) data sharing on HPM effects and target vulnerability; (3) air and maritime defense applications. Japan's HPM program (ATLA Electronic Systems Research Center) develops a phased-array HPM radiation weapon using an active electronically scanned antenna, designed to disable UAV swarms by disrupting electronic circuits. A prototype HPM generator has been built, and outdoor irradiation tests are planned at US test centers under this agreement. JMOD allocated 800 million yen (~$5.2M) in FY2025 for ongoing HPM development. The agreement runs through FY2030, providing a sustained bilateral cooperation framework.

Network Linkage: The US-Japan HPM PA maintains 5 documented connections: signatory ATLA (Japan's defense technology agency); signatory U.S. DoD (US Department of Defense); subject HPM System (the technology being jointly developed and tested). The agreement connects Japan's domestic DEW ecosystem (MHI 10kW laser, KHI 100kW laser, PLASMAGIC plasma generator, railgun) to US test infrastructure and DEW expertise. It complements broader alliance structures: Five Eyes TTCP (plasma-relevant weapons sharing at TRL 1-4), AUKUS Pillar II (EW and counter-hypersonic workstreams), and the Quad (critical/emerging technologies track). The bilateral US-UK DE relationship (dating to 2010) provides a model for the depth of cooperation that the US-Japan HPM PA could eventually achieve.