Recent conflicts in Iraq, Afghanistan, and Chechnya no doubt provided motivation for these books and also make them relevant to a wide variety of readers. The books share some common features but also approach the topic with very different goals in mind. Jeffrey Record and Rod Thornton acknowledge that asymmetric warfare is both an intuitive and subtly complex concept, and both authors are careful to observe what it entails. Their distinctions converge: Asymmetric warfare differs from symmetric warfare in the way the war is prosecuted, not necessarily in a disparity in capabilities (pp. ix, 4). At the same time, both books appear to default to the position that capability disparity and means are correlated, because nonconventional tactics are often chosen by weaker actors, whereas conventional tactics are typically chosen by stronger actors. Thornton's contribution is primarily descriptive, answering the question: “What does asymmetric warfare look like today?” (p. vii). Record's contribution, quite differently, is an analysis of “why the strong lose to the weak” (p. ix). These core differences prevent a direct comparison of the two books, but there are a number of similarities nonetheless.

In Asymmetric Warfare, Thornton methodically discusses the nature of asymmetric threats, as well as possible responses to them in many circumstances. Early chapters discuss the threat from terrorists, with an emphasis on weapons of mass destruction (WMD) and asymmetric information warfare, noting that the biggest threat is from weak state adversaries, rather than individual hackers or terrorist groups (p. 76). Chapters on asymmetry in air (Chap. 4), sea (Chap. 5), and land power (Chap. 6) highlight the fact that conventional forces are not very adaptive, while another focuses explicitly on the issue of asymmetric threats confronted by the United States (Chap. 7). The primary argument throughout the book is that asymmetric adversaries are adaptive, continually developing ways to threaten conventional military means. Stronger actors are not nearly as adaptive but have many operational responses at their disposal. One of Thornton's main arguments is that there are no technological quick fixes in asymmetrical warfare, and that effective strategies require creative political approaches on the ground (pp. 148, 181).

The book's primary strength is that it describes in impressive detail the many ways that current conventional war tactics have become inadequate. Each chapter carefully catalogs many facets of each asymmetric situation. In Thornton's chapter on asymmetry and air power, for example, one key topic is precision-guided munitions (PGMs). He introduces PGMs and then discusses jamming of PGMs, responses to jamming, deceiving PGMs, responses to deception, thwarting PGMs through mobility, responses to mobility, degrees of will and the PGM, and associated responses. The thoughtful attention to the myriad details in each chapter helps deliver one of the key messages of the book: Adapting from conventional to less conventional warfare is extremely difficult. Military approaches to sea power, for example, have always proceeded on the philosophy that “bigger is better” (pp. 102–6), which has until now served great power navies well. But the threat against navies has shifted, requiring different types of warfare, which will be extremely difficult to carry out given existing personnel, infrastructure, and prohibitive costs.

While the author's goal of describing asymmetric threats is successful, the book raises a number of important questions. First, Chapter 1 surveys a number of theoretical arguments about why asymmetric warfare has become more prominent recently but does not devote much time to any one factor (or combination of them). It is unclear which cause(s) the author thinks are most plausible. One consequence of not fleshing out these causes concerns responses that the author proposes in subsequent chapters: They can only be short-term tactical responses, rather than responses that address underlying causes of asymmetric war. Second, although Thornton carefully categorizes a number of important aspects of asymmetric warfare, some choices are puzzling. In discussing the threat from terrorists, for example, the focus is almost entirely on WMDs. And yet, WMDs have been used only in exceptional circumstances, such as Aum Shinrikiyo's use of sarin in the Tokyo subway system, and with only small effects, and there is very little evidence that terrorists have actually acquired (or are close to acquiring) the ability to carry out attacks using WMDs on a scale that represents a substantial threat.

Beating Goliath addresses asymmetric warfare with the goal of understanding why strong powers sometimes lose to weaker powers. The book eschews a monocausal argument and instead contends that a variety of factors, including those discussed in past work, are instrumental in enabling weaker actors to win asymmetric wars. Record contends that victories by weaker asymmetric adversaries depend on external assistance from third parties (his primary argument), stronger political will (argued by Andrew Mack, “Why Big Nations Lose Small Wars: The Politics of Asymmetric Conflict,” World Politics 27 [January 1975]: 175–200), and superior strategy (argued by Ivan Arreguin-Toft, How the Weak Win Wars: A Theory of Asymmetric Conflict, 2005). Record contends that these three factors are necessary (but not sufficient) conditions for victory by weak actors (132). He also adds a discussion of the way the United States fights wars, emphasizing the U.S. aversion to counterinsurgency and its commitment to winning wars regardless of the reasons for their start or the challenges these pose to victory. These additional arguments are interesting, even if not tightly connected to the preceding discussions.

This book's strength is in demonstrating that, indeed, external assistance matters in many cases. In addition to historical cases, Record applies his argument to the Iraqi insurgency (Chap. 3) even though the insurgency was raging at the time of his writing. Events seem to have borne out much of what he argues. He contends, for example, that the insurgency received little support from abroad (p. 71), which implies that it should not succeed. While the success of the insurgency is still debatable, it appears as if it has weakened and been in decline, at least since late 2007 or early 2008, and that the lack of substantial external assistance for the insurgency is one important factor explaining the decline. The author is also cognizant of the fact that disentangling external assistance from stronger will and group strategies is difficult (p. 57). For example, a group with a stronger will might have sought after the external assistance; on the other hand, external assistance might have emboldened the group so that it developed a much stronger will. These possibilities are connected, and Record is careful to acknowledge the dependencies, although little effort is devoted to sorting them out in a systematic way.

The main weakness of the book is the failure to develop each section fully and tie together the various chapters, raising many questions throughout. For example, Record presents no discussion of case selection. Clearly, there are many other wars that could have been discussed, raising the question of whether the ones on which he focused were chosen because they fit the argument best, are representative of all asymmetric wars, or for some other reason. To his credit, Record included examples with and without external assistance, but beyond that, the discussion of case selection is limited, as is the discussion of external support. There is little discussion, for instance, of whether the timing of the external support matters. Is there a critical level of support that can be applied across cases? Here, recent literature on third-party support in civil or interstate wars might offer some insights (e.g., Dylan Balch-Lindsay, Andrew Enterline, and Kyle Joyce, “Third-Party Intervention and the Civil War Process,” Journal of Peace Research 45 [May 2008]: 345–63). Developing these lines of inquiry further would strengthen the central argument.

Furthermore, Record fails to develop at length an interesting point that stands out as a possibility for future research: unintentional external assistance. He suggests that if the stronger side has other commitments—such as in a war with multiple fronts—then this unintentionally assists the weaker side (p. 24). Fleshing out this possibility in greater detail would offer insights into the process of war.

Thornton's book also offers research possibilities. It argues, for example, that asymmetric adversaries have new targets because stronger opponents are often not a single state but, rather, a coalition. Weaker adversaries need not achieve a military victory; instead, they can attempt to weaken the coalition's resolve or cohesiveness (p. 18). Researchers would benefit from the identification of conditions under which coalitions form and survive over time. Thornton also notes that weaker opponents never try to match the technological innovations of their stronger counterparts; instead, they concoct new methods to circumvent these changes (p. 179). He calls for a measure of adaptation to capture these important tactical differences in asymmetric warfare. Developing a measure of asymmetry that incorporates adaptation appears especially important given the assumption of symmetry (and the lack of a discussion of adaptation) underlying much of the work in international relations on war dynamics (e.g., Branislav Slantchev, “The Principle of Convergence in Wartime Negotiations,” American Political Science Review 97 [November 2003]: 621–32).

That said, the topic of asymmetric warfare is of growing importance. And while both books have their drawbacks, both also represent valuable contributions to the literature, and go a long way to advance current debates.