UNCLASSIFIED // PUBLIC RELEASERELEASE 06 · SEPTEMBER 18, 2026
PENTAGON UFO FILE · DOCUMENT · DOW-UAP-D146AAWSAP DIRD, Aneutronic Fusion Propulsion II, November 2010
This DIRD, also dated November 2010, is the second part of the AAWSAP program’s look at aneutronic fusion for spaceflight. Where part one surveyed the physics, this paper takes a systems view: how a propulsion system built around low-neutron fusion fuels might actually be put together and used. The release’s summary of it mentions no sightings.
Fuels, confinement and missions
The paper discusses proton-boron and helium-3 fuels, which produce few neutrons, meaning lighter shielding and the possibility of converting the energy of charged particles directly into thrust or onboard electricity. It reviews the relevant plasma physics and several ways of confining the fusion fuel, then maps them onto missions near Earth, in orbit and between planets.
Its most realistic near-term use, the author concludes, would be very high-power electric or plasma thrusters for satellites and deep-space probes — not aircraft flying in the atmosphere, and not interstellar ships. The obstacles listed run end to end: ignition, keeping the plasma confined, system mass, handling the power, storing fuel, integrating the system with a launch, and engineering the whole package.
About helium-3
Helium-3 is rare on Earth, which is why proposals to use it often mention mining it from the Moon. Read this alongside Aneutronic Fusion Propulsion I and the separate paper on advanced nuclear propulsion.
The official description
From war.gov/UFO, released September 18, 2026, quoted in full
This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed.
This DIRD revisits aneutronic fusion propulsion in a more systems-oriented manner, arguing that fusion concepts using low-neutron fuels such as proton-boron or helium-3 could become attractive for space propulsion because they reduce shielding burdens and may support direct conversion of charged-particle energy into thrust or onboard power. The report reviews the relevant fusion plasma physics and focuses on several candidate confinement approaches, then connects those concepts to possible applications in near-space, orbital, and interplanetary propulsion. It presents the most plausible nearer-term use as very high-power electric or plasma propulsion for satellites and deep-space missions rather than atmospheric flight or interstellar travel, while emphasizing that major obstacles remain in ignition, sustained confinement, system mass, power handling, fuel storage, launch integration, and end-to-end engineering.