Stephen Van Evera

Offense, Defense, and the Causes of War

Is war more likely when conquest is easy? Could peace be strengthened by making conquest more difacult? What are the causes of offense dominance?1 How can these causes be controlled? These are the questions this article addresses. I argue that war is far more likely when conquest is easy, and that shifts in the offense-defense balance have a large effect on the risk of war. Ten warcausing effects (summarized in Figure 1) arise when the offense dominates. (1) Empires are easier to conquer. This invites opportunistic expansion even by temperate powers (explanation A). (2) Self-defense is more difacult; hence states are less secure. This drives them to pursue defensive expansion (explanation B). (3) Their greater insecurity also drives states to resist others’ expansion more aercely. Power gains by others raise larger threats to national security; hence expansionism prompts a more violent response (explanation C). (4) First-strike advantages are larger, raising dangers of preemptive war (explanation D). (5) Windows of opportunity and vulnerability are larger, raising dangers of preventive war (explanation E). (6) States more often adopt fait accompli diplomatic tactics, and such tactics more often trigger war (explanation F). (7) States negotiate less readily and cooperatively; hence negotiations fail more often, and disputes fester unresolved (explanation G). (8) States enshroud foreign and defense policy in tighter secrecy, raising the risk of

Defense Policy and the Reagan Administration: Departure from Containment

I T h e Reagan Administration has proposed the biggest military buildup since the Korean War. The first Administration five-year defense program, drawn up in 1981, would have required an average real budget increase of 8.1 percent per year from 1981 to 1987, for a net real increase of 59 percent. Under this five-year plan, United States defense spending would have risen from 5.6 percent of gross national product (GNP) in 1981 to 7.4 percent of GNP in 1987.’ Later the Administration cut these proposed increases slightly, and Congress is bound to impose further reductions, especially if sizable budget deficits continue. Nevertheless, the Administration has made clear that it favors a major transfer of resources into defense, and the general direction of the Administration budget will continue to be sharply upward. The budget has become the focus of a growing debate over whether the buildup is necessary and whether the new money is well spent. So far this debate has dwelled chiefly on the specifics of Administration proposals. By contrast, we believe that to assess the value of Reagan’s defense policy we must first clarify the United States’ grand strategy: What are America’s basic aims? What missions must the United States military perform to achieve these aims? Can current U.S. forces already perform these missions, or do they fall short? Defense policy cannot be properly evaluated unless national strategy and national military capabilities are specified first. Otherwise-as is generally

Correspondence: Taking Offense at Offense-Defense Theory

I n his article ”Offense, Defense, and the Causes of War,”’ Stephen Van Evera claims that ”offense-defense theory” is ”important,” has “wide explanatory range. . . . wide realworld applicability. . . . large prescriptive utility. . . . [and] is quite satisfying” (p. 41). Van Evera’s conclusions are, however, unwarranted. First, his reformulation of influential arguments made prominent by Robert Jervis stretches the meaning of key concepts such that interesting avenues of empirical inquiry are closed off rather than opened. Second, the hypotheses--or “prime predictions”-Van Evera derives from the theory are themselves products of faulty deductive logic. Furthermore, they are nontestable, presumably nonscientific in Van Evera’s understanding of the term.’ Van Evera’s results are thus of little use to the social scientist who is interested in understanding the myriad causes of war and conditions facilitative of peace. In his classic article, “Cooperation under the Security Dilemma,” Jervis argued that the security dilemma is more virulent and the international system less stable when offense enjoys an advantage over defense. By contrast, when defense is more potent, status quo powers find it easier to adopt compatible security policies, and the pernicious effects of international anarchy are greatly d imin i~hed .~ Although the operation-

Assessing U.S. Strategy in the War on Terror

Al Qaeda and its jihadi allies pose a large threat to U.S. national security. Such a grave menace requires a strong response. Yet the United States has so far waged only a one-dimensional war against al Qaeda, fighting hard on one front when it should be fighting on four. Specifically, the Bush administration has focused heavily on an offensive campaign against al Qaeda overseas while neglecting three other critical fronts: bolstering homeland defense, securing weapons and materials of mass destruction from possible theft or purchase by terrorists, and winning the war of ideas. And the administration has sometimes done too little even on the offensive, instead diverting itself into a costly and counterproductive sideshow in Iraq. The public credits President Bush for toughness on terror. In fact, his administration has pursued a half-hearted war on terror, failing to devote the political and financial resources it requires.Al Qaeda and its jihadi allies pose a large threat to U.S. national security. Such a grave menace requires a strong response. Yet the United States has so far waged only a one-dimensional war against al Qaeda, fighting hard on one front when it should be fighting on four. Specifically, the Bush administration has focused heavily on an offensive campaign against al Qaeda overseas while neglecting three other critical fronts: bolstering homeland defense, securing weapons and materials of mass destruction from possible theft or purchase by terrorists, and winning the war of ideas. And the administration has sometimes done too little even on the offensive, instead diverting itself into a costly and counterproductive sideshow in Iraq. The public credits President Bush for toughness on terror. In fact, his administration has pursued a half-hearted war on terror, failing to devote the political and financial resources it requires.

The Star Wars Controversy: An "International Security" Reader

These essays from the journal International Security assess the technical feasibility and the strategic desirability of defense against ballistic missiles.Originally published in 1986.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.