Filipinos in Manila protest Chinese military installations on disputed islands in the South China Sea on Jan. 24. Eliot A. Cohen argues that U.S. military power can help curb such tensions around the world. (Rolex Dela Pena/European Pressphoto Agency)
Rosa Brooks is a professor at Georgetown University Law Center and the author of "How Everything Became War and the Military Became Everything."

Don’t let the title fool you: Eliot A. Cohen’s newest book, “The Big Stick: The Limits of Soft Power and the Necessity of Military Force,” isn’t a pro-war polemic. Instead, it’s very much in the “older, sadder, wiser” vein: Once seen as a cheerleader for the George W. Bush administration’s ambitious neo-conservative agenda, Cohen now offers a vision of American power largely stripped of illusion. The United States must enhance its military capabilities and remain engaged in shoring up the international order, he contends in this thoughtful and erudite book — but not because it is infallible. It’s simply that in this messy and uncertain world, there are currently no better alternatives.

Even though Cohen is passionate about a United States that is militarily powerful and internationally engaged, he is also a student of history, and for the most part, he owns up to recent U.S. failures. In Iraq and Afghanistan, the United States was “unprepared, intellectually and organizationally.” It made “fundamental misjudgments,” and the military adapted only haltingly and intermittently to the new forms of conflict it faced. Ultimately, Cohen concludes, the Iraq War, which he once staunchly supported, was “a mistake.” False intelligence about weapons of mass destruction damaged U.S. credibility, as did the abuses at Abu Ghraib and elsewhere. More broadly, the war strained civil-military relations, caused tensions with key U.S. allies and left the United States weaker rather than stronger.

Cohen is equally critical of American military and political leaders. Enamored of Special Operations forces and drone strikes, U.S. policymakers have confused tactical success with strategic progress, and the military has failed to invest in “the intellectual infrastructure” of hard power and to develop innovative new ways to bring in vital talent.

Why, then, should the flawed and error-prone United States not simply cultivate its own garden, reserving the use of military force for narrow, defensive purposes?

Cohen has an answer, and it’s far from triumphalist: We live in a country that has been continuously at war for the past 15 years and continually at war throughout its history, and we belong to a species that seems uniquely prone to bouts of mass slaughter. As Leon Trotsky is said to have remarked, “You may not be interested in war, but war is interested in you.” If we take that seriously, the United States needs to be engaged in the ongoing project of shoring up the international order it helped create, and it needs to accept that there may be times when political leaders will conclude, “however reluctantly, that violence is the least bad policy choice.”

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That international order (and the American interests it protects) faces four main challenges. The first is China. China’s worldview is fundamentally incompatible with that of the United States, Cohen asserts. In the South China Sea, for instance, “China has made claims that would not only deny other countries access to the riches of the seabed, but would, by constraining commerce, render them vassals to their giant neighbor.” More broadly, China refuses to “recognize a state system based on equality and sovereignty, and an economic system built around globalized free trade supported by the rule of law.” Instead, “it has a hierarchical conception of international relations.”

China, one supposes, might say the same of the United States. Still, Cohen is surely right that China’s recent attempt to claim most of the South China Sea as part of its territorial waters runs afoul of international law and greatly increases the risk of international conflict. “War,” Cohen notes, “may come without either side willing it from the beginning”; even an “accidental or nearly accidental clash between American and Chinese forces” could quickly spiral into overt conflict, and there is no guarantee that the United States would emerge victorious.

Washington, Cohen contends, must therefore “convince [this] rising, assertive and yet vulnerable peer” that attacks on its neighbors or on the United States would “not only fail, but endanger the regime that launched them,” something that can “only be accomplished by an American force structure, alliance system, and mobilization capacity that makes such attacks self-evidently unwise.”

Cohen sees a second challenge to U.S. interests in the behavior of powerful nuclear and near-nuclear states such as Russia, Iran and North Korea. Each aims to change regional balances of power in ways that could trigger widespread conflict, and each, he argues, can be deterred only by clear evidence that the United States will, if necessary, respond to aggressive or destabilizing actions with decisive force.

In Cohen’s eyes, a third threat is posed by the “various jihadi movements — al-Qaeda, the Islamic State, al-Shabaab, Boko Haram, and others.” Traditional models of deterrence have little to offer when it comes to ideologically motivated, violent nonstate actors, and the United States has struggled both to define and to respond to these nontraditional foes. On the one hand, such extremist groups pose no existential threat to the United States; on the other hand, they can’t merely be ignored. Cohen advocates a combination of “lethal operations . . . to tamp down, disrupt, and limit a virus that cannot, however, be destroyed this way”; a focus on capturing “and where possible, turning” leading terrorists; and a greatly expanded effort to harness American “soft power” to counter extremist ideologies.

Finally, “The Big Stick” turns to the challenges posed by ungoverned spaces and the global commons. Here, there is often no “enemy” but rather a compelling U.S. interest in ensuring that the world’s trouble spots don’t boil over. The refugee flows engendered by Syria’s civil war are destabilizing Europe; internal conflicts in Yemen, Iraq and a dozen other places also threaten regional stability. Similarly, tensions over access to and control of the oceans, over the potentially vast resources beneath the melting polar ice caps, over outer space, and over cyberspace could easily escalate. Complex as they are, Cohen insists, “in all these dimensions of ungoverned space and the commons,” American “military power remains the ultimate guarantor that the diverse great commons of mankind remain accessible to all.”

In some ways, “The Big Stick” is less a defense of the continued relevance of hard power than a broadside against various dangerous illusions. Cohen is scathing, for instance, toward Steven Pinker, Francis Fukuyama and all those inclined to dismiss the 20th century’s brutal world wars as mere random blips in a long-term trend toward peace: “If the world’s randomness is such that it can produce slaughter on such an epic scale,” he asks, “why should we be any less fearful of it in today’s world — a world with far better tools for inflicting mass death?” He is equally savage regarding those who imagine that the use of force can ever be fully predictable or controlled. To Cohen, those who speak of “containment, end state, and exit strategy” are merely sprinkling “a kind of strategic pixie dust” over complex problems, deluding themselves into thinking of war as “a kind of engineering enterprise,” rather than “a contest of opposing wills conducted in the murk of politics,” subject, like everything in human affairs, to “accident, contingency, and randomness.”

No question, U.S. efforts to serve as the guarantor of world order have frequently been characterized by failure and incompetence — but, Cohen reminds us, “failure and incompetence are more the norm in international politics than success and skill,” and in any case, as Syria and a multitude of other tragedies demonstrate, “the perils of inaction . . . can be as great as those of action.”

In a dangerous and uncertain world, he concludes, the best we can do is acknowledge how very little we know and try to build a military and a society capable of rapid adaptation to challenges we can barely anticipate, much less control. To those who ask, “Why the United States?” Cohen offers an implicit challenge: Who else?

The Big Stick
The Limits of Soft Power and the Necessity of Military Force

By Eliot A. Cohen

Basic. 285 pp. $27.99