3. International Cooperation
This chapter examines the United Kingdom's international cooperation frameworks in fusion research, directed energy weapons, and nuclear weapons stewardship. The UK's international position is defined by three major cooperation relationships: AUKUS (trilateral defense technology cooperation with the US and Australia, including DEW cooperation formalized in February 2026), the European Union fusion research relationship (complicated by Brexit but maintained through EUROfusion), and bilateral nuclear weapons stewardship cooperation with the United States (NIF) and France (TEUTATES Treaty). All of these cooperation frameworks are focused on civilian fusion research, conventional DEW development, or nuclear weapons stewardship — none involve plasma orb weapons development.
3.1 AUKUS: Trilateral Defense Technology Cooperation
AUKUS (Australia-UK-US security partnership, est. September 2021) is the UK's most significant defense technology cooperation framework, encompassing nuclear-powered submarines, advanced capabilities, and directed energy weapons. In February 2026, AUKUS DEW cooperation was formalized, extending the trilateral partnership to include joint development and sharing of directed energy weapons technology among the three nations.
The AUKUS DEW cooperation agreement creates a framework for the UK, US, and Australia to collaborate on laser DEW systems, high-power microwave weapons, and related technologies. This cooperation builds on existing bilateral DEW relationships — the UK-US defense technology cooperation and the US-Australia alliance — and creates a trilateral framework that amplifies the capabilities of all three nations. For the UK, AUKUS DEW cooperation provides access to US DEW technology and testing infrastructure, complementing the domestic DragonFire and RFDEW programs.
3.2 EU Fusion Research: EUROfusion and the Brexit Complication
The UK's relationship with European fusion research is complicated by Brexit. The UK hosted and operated JET — the flagship European fusion facility — from 1983 to 2023, but left the European Union and the Euratom framework in 2020. The UK chose not to rejoin Euratom, creating an ambiguous relationship with the EUROfusion research program.
EUROfusion (est. 2014) is the European fusion research consortium that coordinates fusion research across EU member states and associated countries. The UK participates in EUROfusion in an ambiguous capacity post-Brexit — MAST-U is included in the EUROfusion research program, but the UK's full participation status remains unclear. The UK's departure from Euratom also means that the country lost formal access to ITER as an EU member, though the UK has sought alternative arrangements for ITER engagement.
Key relationships:
- EUROfusion includes MAST-U (2020)
- JET validates ITER (1988)
- ITER (est. 1988): International fusion project. UK lost access after Brexit, chose not to rejoin Euratom.
3.3 Nuclear Weapons Stewardship: NIF and TEUTATES
The UK's nuclear weapons stewardship cooperation is centered on two bilateral relationships: the United States through the National Ignition Facility (NIF) and France through the TEUTATES Treaty.
NIF (National Ignition Facility, est. 1997) at Lawrence Livermore National Laboratory is the US's premier ICF facility. AWE collaborates with NIF under the long-standing UK-US nuclear weapons cooperation agreement, conducting joint experiments that support the stewardship of both nations' nuclear stockpiles. AWE scientists participate in NIF experiments, and NIF data informs the UK's assessment of Trident warhead reliability.
Key relationships:
- AWE collaborates with NIF (1997)
- NIF collaborates with AWE (1997)
France cooperation (est. 1995) operates under the TEUTATES Treaty, a bilateral UK-France agreement for joint hydrodynamics experiments supporting nuclear weapons stewardship. The TEUTATES Treaty provides a framework for the two European nuclear powers to share data and conduct joint experiments relevant to maintaining their nuclear deterrents without underground testing.
Key relationships:
- AWE collaborates with France (1995)
3.4 Tokamak Energy's DARPA PUMP: US-UK MHD Technology Link
Tokamak Energy's DARPA PUMP (Portable Utilization of Magnetic Power) contract, awarded in October 2025, creates a significant US-UK technology link in the magnetohydrodynamic (MHD) propulsion domain. DARPA PUMP is a US defense research program aimed at developing compact MHD drive technology for submarine propulsion — using magnetic fields to accelerate conductive fluid (seawater or plasma) to produce thrust without moving parts.
The DARPA PUMP contract awarded to Tokamak Energy, a UK-based private fusion company, demonstrates that the US defense establishment recognizes the relevance of commercial fusion technology to defense applications. Tokamak Energy's expertise in plasma confinement, magnetic field generation, and high-temperature superconducting magnets — developed for civilian fusion energy — is directly applicable to MHD propulsion. This is a clear example of dual-use technology transfer from civilian fusion research to defense applications.
However, MHD propulsion is not a plasma weapon. An MHD drive uses plasma or conductive fluid as a propellant — accelerating it through a magnetic field to generate thrust. The plasma is confined to the propulsion system and expelled as exhaust, not directed at a target as a weapon. The DARPA PUMP contract represents defense-related plasma physics research, but it is a propulsion application, not a weapons application.
3.5 UK Government Investment and Strategic Position
The UK Government has positioned fusion energy as a strategic national priority, committing record funding of 2.6 billion pounds for fusion research in 2025/26. This investment supports UKAEA (STEP, MAST-U), AWE (nuclear weapons stewardship), and Dstl (DEW programs), as well as providing the policy framework for private fusion companies like Tokamak Energy and General Fusion UK.
The UK's strategic position in the global fusion landscape is defined by its combination of government investment, private commercial activity, and international cooperation. The UK is one of the few nations that simultaneously pursues a government-led fusion energy program (STEP), hosts leading private fusion companies (Tokamak Energy, General Fusion UK), maintains a major international tokamak collaboration (JT-60SA with Japan, historical JET with Europe), and participates in trilateral defense technology cooperation (AUKUS). This breadth of activity makes the UK one of the most diverse fusion research ecosystems in the world.
Key relationships:
- UK Government funds UKAEA (1991)
- UK Government funds STEP (2019)
- UK Government funds AWE (1991)
- UK Government funds Dstl (2001)
- Novel Weapons Programme funded by UK Government (2015)
3.6 Position in the Global Plasma Weapons Landscape
In the context of the broader investigation, the UK occupies a significant but non-weapons position in the global plasma weapons landscape. The country has no documented connection to the primary plasma weapons technology pathways — the US MARAUDER/FRCHX/CFR lineage, the Russian Avramenko/Avangard/Stupitskiy lineage, or the Chinese CAE/HFRC/Military-Civil Fusion lineage. The UK's plasma physics activities are divided into three domains: civilian fusion research (UKAEA, Tokamak Energy, General Fusion UK), conventional DEW development (DragonFire, RFDEW), and nuclear weapons stewardship (AWE/Orion).
The UK's contribution to the global plasma physics knowledge base is substantial — through JET's record-setting experiments, MAST-U's Super-X Divertor innovation, Tokamak Energy's FRC/stellarator development, and the historical alternative confinement research (ZETA, HBTX1, SPHEX). However, all of these contributions are civilian in nature and published in the open literature. The UK's DEW programs are conventional systems that do not involve plasma orb weapons concepts.