The demise of Ares—the end of war—has been prematurely announced. A spate of articles and analyses have misread or misrepresented empirical conflict data, failed to frame that data in a meaningful context, and seriously miscast the policy implications of the debate. We believe that there will be no wake for war, and that tomorrow’s security conditions pose numerous challenges to preserving what passes today for peace.
A vibrant debate about the character of future warfare was kicked off several years ago by Harvard psychiatrist Steven Pinker with his bestselling book The Better Angels of Our Nature: Why Violence has Declined (Penguin, 2011). Pinker defines several drivers and a horde of data elements to explain mankind’s evolution from a Hobbesian world of brutish, short, and violent lives to today’s more benign environment. These factors include the formation of states, extended trade, feminization, and the reason and empathy brought about by the Enlightenment (for that small portion of the globe that it impacted). Pinker pummels his reader with an exhaustive number of statistics and myriad arguments.
His thesis is not without numerous counterarguments from scholars, such as Sir Lawrence Freedman, who faults it for failing to consider the power structure of the geopolitical system, and the famous risk analyst Nassim Taleb, author of The Black Swan, who finds that Pinker’s work is not decent statistical analysis but extensive anecdotal aggregation. Causation is casually asserted on multiple fronts but never demonstrated. As one military sociologist observed, Pinker “seldom takes a long and careful look at the larger global and historical context in which decisions about war and peace are made. What we have instead is the rather nebulous and diffuse impact of changing sensibilities.”1
Despite its flaws, it’s a popular book. This has led several authors to jump on Pinker’s line of thinking without absorbing his caveats against predicting the future or recognizing the limitations of its evidence. One author quipped that “war as we know it, long thought to be an inevitable part of the human condition, has disappeared.” Another scholar, Dominic Tierney, has commented, “We are fortunate enough to live in a time of unparalleled interstate peace.”2 According to others, “we live in a remarkably safe and secure place, a world with fewer violent conflicts and greater political freedom than at virtually any other point in human history.” Others contend, inaccurately, that the world today is “less violent than at any point in human history,” due allegedly to “a host of global alliances, a near-universal consensus on international rules and norms guiding the use of force and no true military or political competitor to American power.”3
These statements are factually incorrect, but there are grains of truth in the upbeat assessments of some of these analysts. Human violence has been in significant decline for many years, and especially so in the developed world. The end of the Cold War ushered in a remarkably rare period of peace, with a sharp drop in the number of wars and reductions in the duration and costs of wars. That said, the last 25 years are quite a unique era, and U.S. security and the risks we have to manage are not measured by aggregated global statistics. We must remain concerned with specific threats and keeping them from exploding into large catastrophes. Moreover, as this article will argue, the prognostications above fail to account for possible changes in the emerging security environment.
The context that produced positive trends in the past is evolving, and not in our favor. Contrary to rosy depictions, our alliances are weakening, there is no consensus supported by the authoritarian leaders in Beijing or Moscow about international norms, and competitors are certainly vying for influence in Asia, the Persian Gulf, and along Europe’s frontiers.
Trends are not immutable and they do not proceed in only one direction. Neither global peace nor persistent conflict is preordained.
Looking Backward, Thinking Forward
In our research, we examined the “Correlates of War” database, which is one of the few sources with extended data going back a few hundred years. We particularly examined the 200 years from the Battle of Waterloo to the present. The data showed a “sawtooth” pattern of recurring cycles of increases and decreases in the number of wars of all kinds. Of particular note, we noticed that the present-day low number of conflicts is similar to two previous points in time, the 1850s and the 1930s. Both periods match current levels and debunk the notion that we live in an era of unprecedented peace. More ominously, both periods erupted into violent peaks of greater conflict.4
More contemporary data shows a different pattern, one that requires more insight into context. Figure 1 captures major conflict data from the last half-century. The period 1991 to 2005 illustrates a decline in armed conflicts. However, a closer reading of more recent data from the Uppsala Center shows a plateauing of “armed conflicts” (blue line) and the emergence of an increase in “wars” (red line) in the last decade. The most recent data also shows a notable spike in the number of wars, which suggests that some factors are beginning to drive conflict back upward.5
The data displayed does not support the generic claim that we live in a world in which, per Tierney’s claim, there is a “striking decline in the level of interstate war.” Here again, the claims of the so-called “New Peace” theorists are not supported by the data. Instead, interstate wars have generally been very rare over time, and there has been no significant decline (from a small data population). Moreover, the reason such wars are relatively rare has more to do with the post–World War II international order, first the relatively stable bipolar Cold War era and then the all-too-brief unipolar era. Other databases show the same picture, a leveling in the decline in the number of conflicts, but still low levels of interstate war.6
Even more important for policymakers is the simple caution that, just as in any reputable stock prospectus, past performance is not indicative of future performance. What factors or drivers might cause wars to trend along different paths? Certainly, as Pinker and others have noted, globalization and increased economic interdependence have helped dampen incidents of state-on-state war. But what dark forces might appreciably bend what some see as an ineluctable and linear pattern? Here are several possible other drivers:
American retrenchment. A dominant factor in preserving order and stability over the last 20-odd years has been the unipolar character of the international system. The dominant position of the United States, especially in economic and military power, is the last generation’s most significant characteristic. Whether one calls it a Pax Americana or “America’s Century,” there is little doubt that conflict trends of the last few decades were heavily influenced by a dominant state that exercised extraordinary power under a strategy of deep engagement in order to preserve order. The potential for American retrenchment, amplified with the cuts in defense and foreign-aid spending mandated by existing U.S. law, undercuts the capabilities and capacity that the United States currently has to maintain order. The mere perception of reduced security capacity, much less the actual reduction, could produce instability in regions where existing unresolved political or territorial disputes remain. Other regional powers will emerge to fill in the vacuum produced by reduced U.S. engagement. One of the consequences of that disengagement is an erosion of norms that the United States used to help enforce. Hopefully, this will not produce contagious misbehaviors. We agree with the collective insights of the U.S. intelligence community that the perception of U.S. disengagement or reduced interest is likely to produce an increased chance of interstate conflict. A declining U.S. willingness and/or “slipping capacity to serve as a global security provider would be a key factor contributing to instability.”7 The President’s statement that it was time to focus on “nation building” here at home did little to assuage concerns that Americans are not interested in shouldering their country’s leadership role.
Geopolitical competition. The New Peace theorists entirely overlook geopolitics and the structure of the existing international system. Pinker’s factors overlook the major driver that most security-studies scholars use to explain conflict between states. This inability to address interstate relationships is a gaping hole in the New Peace argument. Again, as noted above, the nature of the international order matters. The Cold War and the more recent period of the Pax Americana were relatively stable. In the emerging multipolar system, with different players in different dimensions (political, military, sociocultural, and economic) and less relative power difference between states, we will likely see a greater propensity to challenge for regional hegemony or to resolve outstanding political grievances.
As Sir Lawrence Freedman has demonstrated in his rebuttal of the New Peace theory, the role of strategic deterrence, military preparedness, and alliances cannot be dismissed. The prevailing power structure has contributed much to subdued levels of interstate conflict and war over the past half-century. Alterations to the current power system by China’s significant economic development and its rapid military modernization could conceivably produce circumstances in which great-power competition (a given) erupts into a war (a possibility). “Historically, transition periods marked by hegemonic decline and the simultaneous emergence of new great powers have been unstable and prone to war.”8 According to Harvard’s Graham Allison, in at least 12 out of 16 cases the emergence of rising powers more often than not produces conflict with the existing predominant powers. The tragedy of great-power conflict can still be avoided, but for evidence of a disturbing trend, it should be noted that in 2012, aggregate military spending in Asia eclipsed that of Europe for the first time in modern history.9
In addition to great-power competition, conflict may arise from acute degrees of nationalism, particularly in Asia. Nationalist sentiment discourages diplomatic compromise, inflates ambition, and fuels distrust between rivals—all paving the way toward miscalculation and aggression.
Declining alliances. Following from the previous driver the role of alliances must be understood. America’s allies and partners have been material contributors to the defense against the security challenge posed during the Cold War. They have been equally material to security in Iraq and Afghanistan over the last decade. Unfortunately, many of America’s traditional allies face social, demographic, and economic challenges. Europe in particular faces a compendium of trends that could produce a suite of partners who are older and smaller demographically, and much poorer in both economic clout and in military spending.
As shown in Figure 2, the E.U.’s economic situation has stabilized and European nations are beginning to recover from 2008. However, their defense spending continues to decline, with calls for austerity in all but a few Baltic States and in Eastern Europe.10 Japan faces many of the same challenges with an aging population and a severe debt-to-GDP ratio that makes increases in security spending most unlikely. Fortunately, our geopolitical competitors are not attractive alliance partners, and are incapable or unwilling to lead allies or make commitments. But to the degree that weak and uncertain alliance structures contributed to disaster in 1914, we face the same problem today and for the near future. Freedman warns that loosened alliance networks and reductions in military preparedness can weaken deterrence and increase the risks of major power conflict.11 For that reason, we adjudge this factor as increasing the possibility of interstate war and its duration.
Technological miscalculation. The evolving character of technology will have a commensurate impact on our security, sometimes in ways we have not yet imagined. Technology is not the sole driver of change in military revolutions, but our age is replete with potentially disruptive sources of innovation that will change how societies fight. Cyber security will be a continual challenge even if it does not technically qualify as a form of warfare, as it can be used to enable or disable crucial elements of our national security and economic system. Cyber deterrence remains tentative despite contrary claims. Redlines, attribution, and proportionality complicate deterrence in this emerging domain, making claims of effective stability entirely speculative.12 Crisis instability appears to be growing, given the uncertain balance of capability between nations and the uncertain character of cross-domain technologies.13 One must ask if the reliance of states on space or cyber connectivity is increasing the need for preemptive actions, which increases crisis instability.
Many of the new emerging technologies such as quantum computing, 3-D printing, robotics, directed energy, and nanotechnology will have military applications, and could prove to be disruptive technologies or “game changers” to the country that first successfully employs them. Due to technological diffusion, the potential exists for serious miscalculation. Indeed, the most likely source of a conflict may be derived from cyber insecurity.14
Resource tensions. Resource pressures are often cited as a source of conflict. It is our judgment that resource competition is a declining source of tension globally, one of the few drivers of conflict that we feel optimistic about. China continues to act assertively in the South China Sea, presumably in the belief that either hydrocarbons or other scarce resources can be found there.15 No doubt Russia still hopes to weaponize its substantial energy resources to coerce European governments to bend to its will. Yet, due to the end of peak demand for fossil fuels, and increased sources in North America and elsewhere, we do not anticipate that oil/gas will stimulate conflict. Instead of energy competition, the future will be marked by greater interest in environmental challenges that impact food security. There is a linkage between environmental impacts, food prices, and political stability, as suggested by scholars who have examined the origins and cascading impacts of droughts and floods in key wheat-growing countries.16 Food security in Asia will continue to grow as a challenge due to rising population requirements and degraded sources of water. Other ongoing conflicts (Syria, for example) have antecedents in ravaged agricultural regions and drought. More recently, ISIS has learned how to use water in Iraq as a weapon.17 Thus, we project an increased likelihood of instability from the nexus of environmental damage, water pressures, and unstable food prices.
Violent extremism. Political violence directed against noncombatants to provoke shock and terror is on the rise, and has been for some time. Groups such as al Qaeda, ISIS, and Boko Haram are filling security vacuums and exploiting political dissatisfaction throughout the Middle East and North Africa. The frequency and lethality of their use of terrorism appears to be escalating, as these groups compete with regional factions and each other for media attention, funding, and recruits. Such extremist violence threatens the domestic security of U.S. partners, disrupts trade, and promotes dangerously revisionist worldviews. As radical groups embrace emerging technologies, the potential for disruption and violence may increase further. And as the head of U.S. intelligence has testified, growing extremism may soon be paired with extreme lethality.18 Though perhaps not enough to incite wars on its own, terrorism and extremist violence is shifting regional power balances, spreading insecurity, and aggravating ethnic and religious animosities, all of which can spiral into new wars.
Today’s violent extremists excel at exploiting weak governments. Failed autocratic governments in the Middle East have been uprooted by the Arab Spring and have created the conditions in several states for violent extremist organizations (VEOs) to make inroads as in Libya and Syria. Other governments in the region will be increasingly tested by populations dissatisfied with governance, legitimacy, or human rights. As the ongoing pyres in Iraq, Yemen, Libya, and Syria indicate, this will most likely lead to increased instability, violence, and the persistence of conflict for some time.
Peacekeeping fatigue. Another factor that could reverse positive trends is the potential for recidivism in conflicts due to the lack of adequate support for peacekeeping operations (PKOs). A large increase in U.N. peacekeeping operations correlates with decline in the number of active conflicts. This is intuitively logical. However, the continued success of U.N. and regional PKOs is predicated upon continued international support, the availability of countries able and willing to provide troops, and the resources to support them. All three requirements could be weakened in the future. International support requires a consensus of major players on the Security Council, which may evaporate in the middle of increased competitions between the West and China or Russia. The availability of troops could decline if major states are unwilling to pay for the operations, or if smaller states face higher security dilemmas at home and cannot sustain external PKOs. Magnus Nordenman from the Atlantic Council puts it well: “. . . a newly assertive Russia and a crumbling Middle East has European decision makers worried that their militaries (exhausted by Afghanistan and shrinking due to budget cuts) may be needed closer to home.”19
Resources and commitments are apparently sliding already. Recently our U.N. ambassador felt it necessary to call for increased assistance levels from Europe in this endeavor.20 Based on current pressures, and foreseeable complexities that will increase the costs of PKOs, we judge it probable that such operations will be fewer, less capable, and hard-pressed to preserve the peace. This will increase the likelihood of both intra and interstate conflict.
A Recipe for Conflict
All told, the combined impact of these trends could generate a return to more significant levels of conflict and increased numbers of casualties and other costs. This is not a complete list, as we have not evaluated the impact of nuclear deterrence on stability, or the potential expansion of nuclear states. Other conditions including poverty, inequality, youth bulges, and poor governance are being examined in a forthcoming larger version of our work. Not all of these drivers will peak at the same time, but several are likely to produce instability and conflict. An unraveling of norms can erode international order and create the conditions for contagious misbehavior. Our analysis matches findings from the collective U.S. intelligence community in its long-range futures forecast. In that forecast, the National Intelligence Council defined prospects for continued stability in clear terms:
…the risks of interstate conflict are increasing owing to changes in the international system. The underpinnings of the post–Cold War equilibrium are beginning to shift. During the next 15–20 years, the U.S. will be grappling with the degree to which it can continue to play the role of systemic guardian and guarantor.21
However, our conclusions are not supported by the recent strategic assessment conducted by our British cousins. In an otherwise typically incisive report, the U.K.’s military futurists sided with the New Peace theorists and concluded:
Although many people see the 20th and early 21st centuries as being the most violent and bloody in human history, evidence suggests that the frequency and intensity of wars, as well as the number of violent deaths, has been declining sharply and is likely to continue to fall.22
We do not dispute the statistical foundation for their statement regarding the last half-century, as both the frequency and costs of wars were distinctly lower, particularly in the 1990s. But we respectfully disagree that these trends are active today, or likely to continue. Moreover, the evidence cited for that conclusion is tied solely to Pinker’s rationale, which is insufficient for projections of state-based conflict. Since the British report was issued, some data about the frequency and violence of contemporary conflict is already reflecting a rise.23 Moreover, the aggregate impact of several relevant drivers suggests that this rise will not abate anytime soon. We hope the ongoing British strategic defense review takes note.
Other studies note the rising dangers of a world in which there is growing friction between rising and established powers, the diffusion of deadly technologies to VEOs, mounting economic pressures, and resource scarcities that could all markedly increase violent conflict.24 We agree with that interpretation, and would add weakened coalitions and reduced peace-support operations as aggravating factors. These drivers could be significant shapers of our future security environment. Such shortsightedness is dangerous; ignoring all these aggravating factors may help justify cutting the very resources that support regional deterrence and contribute to a more stable order. The challenges of deterrence and escalation in the 21st century warrant more study. To overlook this context is dangerous, if not appallingly complacent.25
‘Trend’—or Snapshot in Time?
Our effort here should not be seen as a dystopic exercise. The whole world is not on fire, and foreign forces are not massing on our borders. Certainly, the world is not falling apart, but neither is the scourge of war disappearing. Without any doubt, there was a pattern of declining violence after the end of the Cold War. However, this cycle is not unique to human history and could be reversed, at great cost to ourselves. It appears that levels of conflict are once again increasing and that the contextual tinder for a more contested era of geopolitics is gathering. We should do more to understand how such events have, historically, spun out of control, as in 1914.26
The ahistorical claims about a linear and immutable trend in raw numbers of conflict should be ignored. At best, such a “trend” is merely a reflection of the temperature of the international system at a point in time. In one sense, the recent decline in major conflict frequency is a positive reflection of what we and our allies have been doing for the past generation in terms of working to sustain a rules-based international order. There is a far better case for causation there. But readers should resist the shallow notion that U.S. security interests are tied to the number of ongoing wars. Our security challenges are defined by our strategic objectives, including deterrence and supporting our allies and treaty obligations. The number of current conflicts could be zero right now, and we would still require a military prepared to deter North Korea, assist in the defense of Japan and South Korea, help protect Israel, balance China’s assertive maritime behaviors, and lead NATO in holding Vladimir Putin’s autocracy at bay.
Rigorous thinking about future war requires “a dialogue between the past and the present aimed at illuminating the future.”27 We do not live in the past, but we can be informed by it. We fear too many analysts have preconceived notions drawn from the recent past and hope for a future they prefer to have happen. They have not looked far enough into the past to illuminate tomorrow’s context. If we are going to shed light on what unfortunately could happen in the next decade, we will have to dump the illusions, ideology, and preconceived notions. Closing our eyes to history and its sweeping arcs serves only to ensure that it tries to repeat itself. To paraphrase Mark Twain, the rumor of war’s evolutionary death are greatly exaggerated—and stunningly naïve.
1. Lawrence Freedman, “Stephen Pinker and the Long Peace: alliance, deterrence and decline,” Cold War History, vol. 14, no. 4 (October 2014), 657–72. Nassim Taleb, “The Pinker Problem,” www.fooledbyrandomness.com/pinker.pdf. Ian Roxborough, “The Future of War,” Sociological Forum, vol. 30, no. 2 (June 2015), 464.
2. Bruno Tertois, “The Demise of Ares: The End of War as We Know It?” The Washington Quarterly, Summer 2012, 7. Dominc Tierney, “Is the Whole World on Fire?” Foreign Policy Research Institute E-Note, 14 December 2014, www.fpri.org/articles/2014/12/whole-world-fire.
3. Micah Zenko and Michael A. Cohen, “Clear and Present Safety,” Foreign Affairs, vol. 91, no. 2 (March/April 2012), 80. Michael A. Cohen, “Crisis Inflation: Why the World is Actually Safe for America,” World Politics Review, May 2015, www.worldpoliticsreview.com/articles/print/15758.
4. Meredith Reid Sarkees and Frank Wayman, Resort to War: 1816–2007 (Washington, DC: CQ Press, 2010), http://cow.dss.ucdavis.edu/data-sets/COW-war.
5. Stephen Pinker, “The World is Not Falling Apart,” Slate, 22 December 2014, www.slate.com/articles/news_and_politics/foreigners/2014/12/the_world_is_not_falling_apart_the_trend_lines_reveal_an_increasingly_peaceful.2.html.
6. Charles Krauthammer, “The Unipolar Moment Revisited,” The National Interest, Winter 2002/03, 5–17. David A. Backer and Paul K. Huth, “Global Trends in Armed Conflict, 1946–2012,” in David Backer, Jonathan Wilkenfeld, and Paul K. Huth, Peace and Conflict 2014 (Boulder, CO: Paradigm, 2014), 18–22.
7. Global Trends 2030: Alternative World (Washington, DC: National Intelligence Council, 2012), viii, www.dni.gov/index.php/about/organization/global-trends-2030.
8. Freedman, “Stephen Pinker,” 659. On Chinese actions and naval modernization, see Toshi Yoshihara and James R. Holmes, Red Star Over the Pacific: China’s Rise and the Challenges to Maritime Strategy (Annapolis, MD: Naval Institute Press, 2010), and CAPT Bernard Cole, USN (Ret.), The Great Wall at Sea: China’s Navy in the Twenty-first Century, 2nd ed. (Annapolis, MD: Naval Institute Press, 2010) Christopher Layne, “Sleepwalking with Beijing,” The National Interest, May/June 2015, 45.
9. Graham Alison, testimony before the Senate Armed Services Committee, 14 April 2015, www.armed-services.senate.gov/imo/media/doc/Allison_04-14-15.pdf. Adam Liff and G. John Ikenberry, “Racing Toward Tragedy? China’s Rise, Military Competition in the Asia Pacific, and the Security Dilemma,” International Security, vol. 39, no. 2 (Fall 2014), 53.
10. Olivier de France, “Defence Budgets in Europe: Downturn or U Turn,” EU Institute for Security Studies, Issue Brief 12, 15 May 2015, www.iss.europa.eu/uploads/media/Brief_12_Defence_spending_in_Europe.pdf.
11. Freedman, “Stephen Pinker,” 661.
12. Zachary Davis, Ronald Lehman, and Michael Nacht, eds., Strategic Latency and World Power: How Technology is Changing Our Concepts of Security (Livermore, CA: Lawrence Livermore National Laboratory, 2014). Thomas Rid, Cyberwar Will Not Take Place (London: Hurst, 2013). David Gompert and Martin Libicki, “Cyber Warfare and Sino-American Crisis Instability,” Survival, vol. 4, no. 56 (Summer 2014), 7.
13. Avery Goldstein, “First Things First, China: The Pressing Danger of Crisis Instability in U.S.-China Relations,” International Security, vol. 37, no. 4 (Spring 2013), 49–89. Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyberspace Fit?” National Defense University Strategic Forum, no. 272 (December 2011), http://digitalndulibrary.ndu.edu/cdm/ref/collection/ndupress/id/45581.
14. Shawn Brimley, Ben Fitzgerald, and Kelley Sayler, Game Changers: Disruptive Technology and US Defense Strategy (Washington, DC: Center for a New American Security, 2013) http://www.cnas.org/game-changers#.Vjj6iiuMJtA. Michael C. Horowitz, “Coming Next in Military Tech,” Bulletin of the Atomic Scientists, vol. 70, no. 1 (January/February 2014), 54–62. Damien Palleta, “When Does a Hack Become an Act of War?” The Wall Street Journal, 13 June 2015.
15. Meghan L. O’Sullivan, “The Entanglement of Energy, Grand Strategy, and International Security,” in Andreas Goldthau, ed., The Handbook of Global Energy Policy (New York: John Wiley & Sons, 2013), 30–47. “Beijing Zeroes In on Energy Potential of South China Sea,” The New York Times, 28 October 2014.
16. Thomas L. Friedman, “The Scary Hidden Stressor,” The New York Times, 2 March 2013.
17. Monika Barthawal-Datta, Food Security in Asia: Challenges, Policies and Implications (London: International Institute for Strategic Studies, 2014), www.iiss.org/en/publications/adelphi/by year/2013-7c11/food-security-in-asia-d8fc. Kahmira Gander, “ISIS Uses Water as a Weapon in Iraq, by Closing Dam Along Euphrates,” The Guardian, 3 June 2015.
18. Dan Byman and Jennifer Williams, “Al-Qaeda vs. ISIS: The Battle for the Soul of Jihad,” Newsweek, 27 March 2015, www.newsweek.com/al-qaeda-vs-isis-battle-soul-jihad-317414. James Clapper, Director of National Intelligence, “Worldwide Threat Assessment of the U.S. Intelligence Community,” statement to the U.S. Senate Select Committee on Intelligence, 29 January 2014.
19. Magnus Nordenman, “Why the West Will Ignore Samantha Power’s Call for U.N. Peacekeepers,” Defense One, 12 March 2105, www.defenseone.com/ideas/2015/03/why-west-will-ignore-samantha-powers-call-un-peacekeepers/107409.
20. “U.S. Ambassador to U.N. Pushes Europe for More Peacekeepers,” The Wall Street Journal, 9 March 2015.
21. Global Trends 2030.
22. Strategic Trends Programme: Global Strategic Trends—Out to 2045 (Shrivenham, UK: Ministry of Defence, 2014), 96, www.gov.uk/government/publications/global-strategic-trends-out-to-2045.
23. Peter Apps, “Breaking a Decades-Long Trend, the World Gets More Violent,” Reuters, 20 March 2015, http://blogs.reuters.com/great-debate/2015/03/20/breaking-a-decades-long-trend-the-world-gets-more-violent.
24. Paul B. Stares and Micah Zenko, Partners in Preventative Action: The United States and International Institutions (New York: Council on Foreign Relations, 2011), 3.
25. LtCol Frank G. Hoffman, USMCR (Ret.), “Culpable Complacency & U.S. National Security Strategy,” War on the Rocks, 31 December 2013, http://warontherocks.com/2013/12/culpable-complacency-u-s-national-security-strategy. Forrest E. Morgan, Karl P. Mueller, Evan S. Medeiros, Kevin L. Pollpeter, and Roger Cliff, Dangerous Thresholds: Managing Escalation in the 21st Century (Santa Monica, CA: RAND Project Air Force, 2008).
26. Margaret MacMillan, “The Rhyme of History: Lessons of the Great War,” Brookings Institution, 14 December 2013, www.brookings.edu/research/essays/2013/rhyme-of-history.
27. Michael Evans, “Forking Paths: War After Afghanistan,” Parameters, vol. 44, no. 1 (Spring 2014), 77–94.