president-elect donald trump does not speak softly, but he clearly believes in military power<u+2014>what theodore roosevelt called <u+201c>the big stick.<u+201d> like all of his predecessors, however, he will soon discover that it isn<u+2019>t enough to brandish armed force: he will find himself having to use it. on jan. 20, mr. trump will inherit three wars: iraq, afghanistan and the global campaign against various jihadist movements. he will also have to make decisions about other flashpoints that could, willy-nilly, drag the u.s. into armed conflict: iran<u+2019>s efforts to dominate the persian gulf, north korea<u+2019>s drive to build a nuclear-armed long-range missile, china<u+2019>s aggression in the south and east china seas and, yes, his friend vladimir putin <u+2019>s bullying of our nato allies in the baltics. as he prepares to take office, mr. trump needs to do some hard thinking about 21st-century warfare and strategy. i should say that, along with many other republican national-security experts, i publicly opposed mr. trump<u+2019>s bid for the presidency, and i have not been encouraged by the start he has made in assembling a national-security team for his administration. for all my concerns, however, i have no reason to think that mr. trump is eager to wage war. he is smart enough to be aware of its hazards. but even a president as averse to the use of military force as barack obama ended up being a war president: he massively expanded targeting killing with drones, intervened to overthrow the libyan regime, prolonged the u.s. commitment in afghanistan and has now re-engaged in iraq to take on islamic state. mr. obama no doubt felt that he had little choice, and mr. trump will feel the same pressures. mr. trump<u+2019>s challenge is harder because he has no foreign-policy experience and no clear worldview. there is no trump doctrine, nor is there likely to be one. nor is there, among his confidantes, a would-be henry kissinger or dean acheson to develop a larger u.s. strategy. when it comes to the use of military force, the temptation for the trump administration will be to resort to a famous set of guidelines proposed more than three decades ago by another republican administration. on nov. 28, 1984, secretary of defense caspar weinberger, the trusted cold war adviser of president ronald reagan, laid out principles that have come to be considered a classic statement of how and when the u.s. should bring its might to bear: first, the united states should not commit forces to combat overseas unless the particular engagement or occasion is deemed vital to our national interest or that of our allies. second, if we decide it is necessary to put combat troops into a given situation, we should do so wholeheartedly, and with the clear intention of winning. third, if we do decide to commit forces to combat overseas, we should have clearly defined political and military objectives. and we should know precisely how our forces can accomplish those clearly defined objectives. and we should have and send the forces needed to do just that. fourth, the relationship between our objectives and the forces we have committed<u+2026>must be continually reassessed and adjusted if necessary. fifth, before the u.s. commits combat forces abroad, there must be some reasonable assurance that we will have the support of the american people and their elected representatives in congress. finally, the commitment of u.s. forces to combat should be a last resort. weinberger<u+2019>s guidelines sound sensible and impressively prudent; they rightly focus on the connection between means and ends, as must any effective strategy. but that isn<u+2019>t enough. weinberger<u+2019>s vision of warfare has never held up well to scrutiny, and it would be a mistake for president trump, or any other commander in chief, to follow it. the first of weinberger<u+2019>s guidelines, requiring that force be used only to serve vital u.s. interests, is almost infinitely elastic. anything<u+2014>from a loss of american prestige to the protection of american citizens, from attempts to deter aggression to even minimal efforts to fulfill our treaty commitments<u+2014>can be defined as vital either to us or to our allies. the next requirement<u+2014>that we should always engage <u+201c>wholeheartedly<u+201d> and be intent on <u+201c>winning<u+201d><u+2014>would mean that, rather than picking off terrorists one by one in their distant desert redoubts, we should invade the countries that harbor them. this isn<u+2019>t exactly what the american public yearns for just now, nor is it prudent to take such an all-or-nothing approach. weinberger<u+2019>s principle also assumes that winning is an unambiguous term; no military historian would agree. as for knowing <u+201c>precisely<u+201d> how the u.s. is going to achieve its objectives, that is impossible, because the enemy also has a say. as winston churchill observed, <u+201c>always remember, however sure you are that you could easily win, that there would not be a war if the other fellow did not think he also had a chance.<u+201d> in war, some political objectives are almost always concealed, often within the head of a single decision maker. during the 1991 gulf war, president george h.w. bush wanted to see the iraqi dictator saddam hussein overthrown, but he never said so, for good reason: mr. bush wasn<u+2019>t sure he could deliver regime change, and he hoped that the iraqi military would do the job for him. weinberger was right that it makes sense to keep track of whether available forces remain adequate to stated ends. but doing so <u+201c>continually<u+201d> would take up far too much of the precious time of senior decisionmakers, whose attention should be focused instead on dispatching forces, coordinating with allies, reacting to emergencies, devising strategy and assessing battlefield results. as for <u+201c>reasonable assurance<u+201d> of the american people<u+2019>s support, there is no way to guarantee in advance that the public will rally to any particular war. indeed, political scientists have shown that public support often follows military success rather than preceding it. and finally, war is never a last resort. as clausewitz noted long ago, war is always an intermediate choice. after all, we could always just concede our objectives: we could let the iranians dominate the persian gulf, or let islamic state rule northern iraq or let al qaeda re-establish itself in afghanistan. weinberger<u+2019>s guidelines have endured because of their simplicity and clarity, but for all that, they are mostly wrongheaded. mr. trump is famous for relying on his instincts, but he would be better served, as he takes office and assumes the role of commander in chief, by guidelines adapted to the 21st-century realities that he will face. understand a war for what it is, not what you wish it to be. clausewitz said that the most dangerous error one can make in wartime is mistaking one kind of conflict for another or <u+201c>attempting to turn it into something alien to its nature.<u+201d> in iraq, it took years for u.s. leaders to accept that we were dealing with an insurgency and then a sectarian civil war, not desperate resistance by <u+201c>bitter-enders<u+201d> loyal to saddam. in today<u+2019>s struggle against jihadists, we will make lasting progress only when our strategy includes not just military operations but a concerted effort to confront their religious ideology<u+2014>a dimension of the conflict that too many political leaders do not understand or are reluctant to recognize. planning is important, but adaptability is crucial. churchill observed that <u+201c>it is not given to human beings<u+2026>to foresee or to predict to any large extent the unfolding course of events.<u+201d> individual leaders and institutions alike must be ready to change in wartime. president george w. bush<u+2019>s great moment as commander in chief didn<u+2019>t come when he approved the initial invasion plans for afghanistan or iraq. it came several years later, in 2006, when he decided to surge more u.s. troops into iraq to avert defeat<u+2014>a tough call, taken against the advice of many of his commanders and advisers. prepare for tomorrow<u+2019>s war. military history is replete with examples of armies that, having won one kind of conflict, find themselves unready for something different. in its 2006 campaign against hezbollah in southern lebanon, for instance, the israeli army did badly in part because its troops had lost their combat edge during years of conducting much less demanding operations in the west bank and the gaza strip. by contrast, it was the u.s. army<u+2019>s turn from counterinsurgency to a focus on conventional combat after the vietnam war that helped to make the 1991 gulf war a swift and overwhelming victory. be ready to go long. americans like swift, sharp conflicts like operation desert storm: they suit our impatient national character and play to our tremendous technological and operational strengths. for precisely that reason, our enemies will always try to drag out a conflict, and we won<u+2019>t always be able to stop them. having defeated saddam in 1991, american leaders thought that we would then be done with iraq. we are still there. accepting the reality of long-lasting wars is particularly important in tackling the jihadist problem. australia<u+2019>s former army chief, peter leahy, recently described it as a <u+201c>100-year war<u+201d> against radical islam. that is a staggering thought, but it is probably what we face. perseverance usually matters more than adroit strategy. staying power is essential. leaders rarely see victory (or defeat) coming; it is virtually impossible to know when or how wars will conclude. but great wartime leaders such as lincoln, clemenceau and churchill shared an iron determination to see their war efforts through. and they understood that it was their job to instill a similar will to win in their subordinates<u+2014>sacking those who lacked it, bolstering those whose spirits flagged, promoting generals who had the necessary grit. presidents can launch wars, but they cannot win them without broad support. on one score, weinberger was half right: in a republic, popular support for a war is essential. but a president can never count on it; he must win it through regular, energetic argument and explanation. in this respect, mr. trump<u+2019>s two predecessors failed. presidents bush and obama gave strikingly few speeches explaining to the american people the nature of the wars they led. we often remember churchill<u+2019>s wartime speeches for their ringing phrases, but they are equally notable for the effort that he put into explaining to the british people, and the world, what world war ii was about, how it was going and where it might go. in an age when attacks can be launched on a president<u+2019>s say-so, formal congressional declarations of war can seem quaint. but congressional authorization for the use of military force is another matter. both presidents bush sought and received it for the 1991 and 2003 wars with iraq. regrettably, mr. obama didn<u+2019>t try hard enough to win it or simply didn<u+2019>t want it for libya and the current fighting in iraq. this evasion of wider accountability is a terrible mistake, and not just because article i of the constitution explicitly gives congress the power <u+201c>to declare war.<u+201d> when wars go badly (and at some point, and for some time, they almost always do), there is no better support for morale in the military and resolve in the public than knowing that the people<u+2019>s representatives have shared in the decision. like most presidents, donald trump is likely to face that awful moment when he will need to send young american men and women off to war, where some will be wounded and others killed. some presidents regularly visit the military hospitals; others are reluctant to do that too often for fear of distorting their judgment. none has ever taken lightly the deployment of the u.s. military, and i doubt that mr. trump will. the bigger question is whether mr. trump will put in the effort to remedy his lack of preparation for commanding the u.s. military. despite the hand-wringing of the campaign, this is hardly the most dangerous period in american history<u+2014>but it is dangerous enough. an untutored new president faces a nationalistic china, a turbulent islamic world, a belligerent russia, a not-entirely-sane north korea and a range of new threats, such as cyberattacks and antisatellite weapons. old alliances are in jeopardy, and not just because the president-elect considers them bad deals that need to be renegotiated or dropped. mr. trump may enjoy hearing <u+201c>hail to the chief<u+201d> the first few times, but he will soon realize that it comes with a heavy burden. we must all hope that a man who reputedly doesn<u+2019>t read much will have others around him who do, and that he will begin to school himself on what it takes to wage wars<u+2014>because he will surely find himself directing several of them. dr. cohen is robert e. osgood professor at johns hopkins university<u+2019>s school of advanced international studies and worked for secretary condoleezza rice as counselor of the department of state in 2007-09. this essay is adapted from <u+201c>the big stick: the limits of soft power and the necessity of military force,<u+201d> which will be published next month by basic books.
when president trump goes to war - wsj
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