Air University Press

War at the Speed of Light: Directed Energy Weapons and the Future of Twenty-First-Century Warfare

War at the Speed of Light: Directed Energy Weapons and the Future of Twenty-First-Century Warfare by Louis A. Del Monte. Potomac Books, 2021, 269 pp.

Modern warfare can be characterized by the compression of battlefield time and space resulting in rapid resource attrition and the need to react faster to adversary actions. War at the Speed of Light by Louis Del Monte provides a top-level survey of strategic options incorporating faster weapons, the technical capabilities for directed energy weapons, and what future wars may look like if these weapons are fielded. The book first examines US offset strategies and progress toward implementing fourth offset goals. Each weapon category, from laser to cyberspace, appears with a detailed technical description as well as US and adversary progress toward fielding battle-ready options. The final section examines the potential of autonomous weapons and considers what directed-energy fights across the ultimate high ground of space may entail. Del Monte’s book is an easily read overview for those interested in future technologies and should be on the read list for those studying the art of war, potentially making a good mandatory read for those in some Space Force basic technical schools.

The central theme behind War at the Speed of Light is that electromagnetic spectrum weapons rather than physical projectiles should be a core component of any forward-looking US strategy. The book does not advance a thesis or tested point but instead presents the strengths and weaknesses of these weapons. The core discussions consider means rather than ends, leaving out any potential operations employing speed-of-light weapons. While various scenarios are discussed, most are on a personal basis versus a military use case. There is no direct comparison between US and adversary systems. Therefore, the book is a primer on potential possibilities rather than a full evaluation of which systems are preferential for future military success.

The first section addresses the four US offset strategies from a chronological perspective. The first offset strategy was deterrence as characterized by nuclear Cold War options, including mutually assured destruction and other nuclear strategies. The second offset strategy emphasized precision when laser and GPS targeted weapons appeared in the first and second Gulf Wars. Transitioning to the third offset began under President Obama with the Strategic Capabilities Office and increased funding for the Defense Advanced Research Projects Agency (DARPA). This strategy sought technical advances by reaching out to commercial partners to field the most modern technology. The fourth offset started with President Trump and included three changes to the previous offset. It recognized China and Russia as the greatest threats to US national security, emphasized directed-energy weapons as essential, and secured alliances as an asymmetric strategic advantage. Each offset had an advantage when it was proposed. It  remains to be seen whether the US will remain committed to the newest change or seek a different offset.

After establishing a strategic framework, Del Monte looks at four directed-energy weapon categories: laser, microwave, electromagnetic pulse, and cyberspace. In the laser category, the author primarily examines blinders but also touches on the US Navy’s anti-drone capability. Not mentioned are the US Army’s recent acquisitions, including the Multi-Mission High Energy Laser (MMHEL) and the Stryker-mounted air defense systems. The author next introduces microwave weapons–especially their use for crowd control through the neurological impacts possible. An excellent example appears with the Cuban use of these weapons against the US embassy in Havana that caused physical illness, vertigo, and some sensory damage. Electromagnetic pulse weapons, the third category, use an intense burst of energy to nullify electronics. These effects are referenced as created from a secondary effect of nuclear explosion vis-à-vis an independently fielded weapon. The final weapon category, cyberspace, encompasses a broader field although the author mentions more traditional electronic attacks like the jammers employed by the EA-6B Prowler. I consider cyberspace weapons too diverse to adequately cover in a single chapter as a subcomponent of directed energy weapons due to the many options with directed effects, hunting systems, and intelligence options. Del Monte spends a paltry 23 pages in two chapters examining defensive options as standard electronic countermeasures before mentioning active defense systems to protect from either kinetic projectiles or electromagnetic radiation. Each element of the technical capabilities is sufficiently referenced to allow readers to seek out more detailed data from other sources.

The final section explores the technological near future by characterizing the challenges posed by autonomous weapons and killer satellites. Del Monte mentions the ethical dilemmas associated with weapons picking their own targets and what could happen when weapons can strike faster than the longer, human-driven kill chain required by today’s autonomous weapons, such as the Tomahawk cruise missile. Left out is the discussion of whether a fire-and-forget weapon is an autonomous option or simply improved aiming. Space weaponization suggests the potential for satellites to maneuver to physically destroy an adversary or perhaps for particle beam employment. High velocity in orbit means that any object capable of navigation could be used as a kinetic weapon. Particle beams use high-energy directed weapons with increased effectiveness because of the absence of any atmospheric interference. Del Monte concludes with three guidelines for future war: (1) nuclear weapons should be eliminated, (2) autonomous weapons should be used solely under close human supervision, and (3) all autonomous weapons should employ only conventional warheads.

Most texts I review begin with a strategic proposition and advocate for those principles throughout the work. War at the Speed of Light offers a more generic look at future capabilities. In my view, the biggest limitation is the concentration on isolated tactical employment versus a strategic or combined arms perspective. Each section introduces the topic but lacks depth on how the weapons might be employed or where they would instead serve as a force multiplier. As an example, cyber weapons typically serve as force enhancement, providing enhanced ISR or allowing conventional systems to strike more effectively. A more coordinated discussion on the concepts in several scenarios such as in Space Wars: The First Six Hours of WWIII by Coumatos, Scott, and Birnes (2007) would have made the book more effective and meaningful to the reader.

Overall, War at the Speed of Light offers a good introduction to those whose background in the area is lacking. The summary of the US strategic offsets is excellent. The technical capabilities, offensive and defensive, provide enough detail for the reader to find other sources to seek more detailed knowledge. Lacking any comparison of how the different weapons might be employed in a combined arms strategy, the final section fails to muster sufficient emphasis to serve as true guideline for a way ahead when considering the proposed weapon systems. The book provides an excellent starting point, and I would recommend it for those new to the study of war or looking to begin researching directed-energy capabilities.

Dr. Mark T. Peters II, USAF, Retired

"The views expressed are those of the author(s) and do not reflect the official policy or position of the US government or the Department of Defense."

Strategic Studies Quarterly (SSQ) and the Air & Space Power Journal (ASPJ) publish book reviews to inform readers and enhance the content of articles in the journals.