War’s political nature requires military strategists to resolve the tension between war as a deadly competition—demanding maximal expenditure of force—and political restraints intended to limit destruction, maintain a coalition, or shape the subsequent peace.[1] This tension is prominent when states employ air power in limited wars and coercive campaigns such as Operation Allied Force. The imperative to balance military strategy (seeking victory) with grand strategy (seeking a better state of peace) limits military options—yet achieving that balance is vital to enduring success.[2] As they perform that balancing act, strategists will continue to find that even in limited wars, air power should pursue positive objectives to achieve maximum leverage over the enemy. Operation Allied Force gives us a story of strategists doing their part to maximize military effectiveness in an uncertain, complex political scenario.

…military strategists must understand the reasoning behind specific restraints, and maximize the utility of their forces within those restraints…

Most wars are limited wars, with significant political restraints on military force. Such restraints create conundrums for military strategists. “The less intense the motives,” wrote Carl von Clausewitz, “the less will the military element’s natural tendency to violence coincide with political directives.”[3] Yet, as Allied Force illustrates, the savvy strategist can maximize the effectiveness of the air weapon even when political will is weaker.

When the strategist must uphold democratic values and manage coalition concerns, some political restraints may be necessary for air power to serve its strategic purposes. For this synergy to occur, military strategists must understand the reasoning behind specific restraints, and maximize the utility of their forces within those restraints. That said, if certain restraints jeopardize the operation or render the air weapon ineffective, then air power strategists have a duty to make that case to their leaders. Allied Force proves air power can be a strong coercive means even when political will is tepid or political strategy is initially unclear—if military strategists can still discern positive objectives, and generate maximum leverage in their pursuit.

Leverage is smarter and more effective than brute force; it requires aggressively executing air power actions that serve clear strategic ends.[4] Maximum leverage does not necessarily mean maximum destruction, nor does it mean the indiscriminate use of force.[5] Rather, leverage is highly contextual. Air power contributes to maximum leverage “when it is targeted toward that which is most valuable to leaders…harkening back to Clausewitz’s idea of ‘centers of gravity.’”[6] Again, context matters—one state’s army may be its center of gravity, while others may be mere cannon fodder.[7] Generating maximum leverage requires knowledge of the specific enemy’s sources of political and military power.

To generate maximum leverage and achieve the desired strategic effects, air power should be employed in a multi-domain scheme with other military tools and instruments of power. In such a strategy, component positive objectives reinforce each other, putting the adversary on “the horns of a dilemma.”[8] Achieving air superiority opens maneuver space for friendly forces and renders more enemy assets vulnerable to attack.[9] Destroying state communications, security, and political apparatus may threaten the target regime’s hold on power, making capitulation more palatable. Attacking the assets and interests of the political inner circle in an autocracy or kleptocracy may weaken the regime’s cohesion and resolve.[10] Isolating an enemy politically may remove the last hope for effective resistance. These principles proved valid—if not always easy to enact—in NATO’s air campaign over Kosovo. 

Operation Allied Force

Air forces are active instruments that best serve positive objectives. Political and military leaders can expect results when they direct air forces to achieve something physically different from initial conditions—establish air superiority, destroy a target set, resupply a group of people, and so on.

On the other hand, as Professor Mark Clodfelter of the National War College points out, air power is poorly suited to negative objectives, which correlate with lower levels of political will and restrain military force.[11] Military strategists should advise against plans that demand air power prevent something from happening, or avoid escalating a conflict, or demonstrate an esoteric property such as “seriousness” while minimizing risk and cost. Such negative, passive, or nuanced objectives translate poorly to operational and tactical actions.

Air power has proven its great value in limited wars due to its range of useful functions. But air power is a poor means of political bargaining or sending nuanced messages, because in such cases, too many negative objectives conflict with the proactive nature of air power.[12] Allied Force provides a case study on the effect of restraints and limited will on a military operation, and how military strategists should navigate such situations.

Allied Force was a NATO operation in the spring of 1999. NATO aimed to coerce Yugoslav President Slobodan Milosevic into ceasing his Serbian forces’ ethnic cleansing campaign against Kosovar Albanians, and resuming negotiations over Kosovar political autonomy. NATO political and military leaders from the period admit that at the outset, their strategy for using force was unclear. Political leaders believed Milosevic would quickly capitulate once NATO began bombing; as a result, they initially failed to connect air power means to desired political ends.[13]

As the campaign began, U.S. President Bill Clinton articulated three objectives (only one of which clearly translates to operational and tactical air power actions):

• To demonstrate the seriousness of NATO’s purpose;

• To deter an even bloodier offensive by Yugoslavia against Kosovar civilians; and

• If necessary, to seriously damage Serbia’s military capacity.[14]

NATO would eventually codify five objectives, a mix of positive and negative, some more aspirational than attainable:

• Halt Serbian ethnic cleansing in Kosovo;

• Cause the withdrawal of Serbian forces from Kosovo;

• Enable the deployment of a NATO peacekeeping force;

• Enable ethnic Albanian refugees to return to their homes in Kosovo; and

• Lay the groundwork for a political settlement including Kosovar autonomy.[15]

Clinton and other NATO leaders often spoke of their intent to demonstrate NATO’s resolve or seriousness through aerial bombardment.[16] Yet at the same time, those leaders publicly eschewed the deployment of a NATO ground combat force, due to their perception of widespread casualty aversion among their domestic populations and a fear that too forceful a play would fracture the coalition.[17] To many, including Milosevic, the declaration that NATO would not deploy a ground force signaled a lack of coalition political resolve, as did the early air effort’s limited target list and gradual pace.[18]

Acknowledging NATO’s collective hesitancy to use force, the bombing plan departed from the U.S. Air Force ideal of simultaneous, shock-inducing strikes against air defenses and priority targets. Instead, three distinct phases were planned: first, attacks on Serbian air defenses; then, attacks on military targets in and around the disputed region of Kosovo; and finally, if necessary, military and priority targets in the Serbian homeland and the capital, Belgrade. This gradualist use of air power would become “highly contentious” as the campaign progressed.[19]

On the first night, 24 March 1999, NATO attacked just 40 Serbian targets—mostly air defense and radar systems.[20] The following two weeks saw more successful strikes against Serbian air forces, air defenses, and fixed military targets. These strikes opened maneuver space for NATO air forces; meanwhile, the Serbian ground assault on Kosovar Albanians actually intensified.[21] Though the coalition remained intact politically, the military operation was not achieving its objectives.

The lack of a ground force complicated the air component’s task of finding and striking Serbian fielded forces. Because there was little pressure on the ground forcing the Serbs to maneuver or mass, the Serbs were able to remain concealed from NATO aircraft, or exploit NATO’s observance of the laws of armed conflict by positioning tanks and artillery among concentrations of civilians.[22] The region’s rugged terrain and poor flying weather aided the Serbs’ concealment. The joint force commander, U.S. Army General Wesley Clark, along with Air Force component planners, began to advocate more vocally for a conventional ground component.[23]

To summarize, the early weeks of Allied Force did not resolve tensions between the use of force and political restraints. Political restraints ruled the day. As a result, the objectives were not positive enough, and leverage was inadequate. The coalition had achieved air superiority and executed many tactically successful strikes within its limited target list, but the overall effort was not achieving the desired political results.

Milosevic’s continued non-compliance frustrated NATO political and military leaders enough for them to escalate the war. With political resolve increased, air component commander Lieutenant General Mike Short and his staff expanded the effort into a true air campaign. They struck an array of so-called Phase 2 and 3 targets, including state media, internal security headquarters, and the Yugoslav economy (i.e., fuel, electricity, industry, and infrastructure).[24] With its air defenses crippled, the Yugoslav military stood powerless to defend economic, industrial, and private assets treasured by Milosevic and his powerful circle of political elites.[25] Precise weapons employment against such targets maximized the campaign’s leverage.[26] Furthermore, an indigenous Kosovar ground force of a few thousand irregulars launched ambitious attacks against the Serbs, while NATO political leaders publicly discussed the deployment of a conventional ground force of their own.[27] This combined application of military means increased the leverage of the campaign by reducing the benefits of continued control over Kosovo and raising the costs for Milosevic and his cronies. NATO maximized its leverage over Milosevic through this escalated air campaign.

U.S. Air Force Chief of Staff General Michael Ryan summarized the campaign’s overly-restrained start, and the turn: “The campaign did not begin the way that America would normally apply air power—massively striking at strategic centers of gravity that support Milosevic and his oppressive regime. A month into the campaign, it became apparent that a constrained, phased approach was not effective. NATO broadened the campaign to achieve strategic effects.”[28]

Milosevic capitulated on 9 June 1999. Most analysts and historians agree several factors combined to force Milosevic’s capitulation. The most commonly cited factors are:

• The escalated air campaign, and the Serbs’ inability to defend against it;

• The resulting erosion of domestic support for Milosevic, particularly among his circle of kleptocrat elites;

• The United Nations’ indictment of Milosevic as a war criminal and his loss of Russian political support; and

• The looming threat of ground invasion.[29]

Each of these factors involved a specific coercive mechanism—linking of a positive objective to increased leverage or advantage over the enemy.[30] Yet air power was “the indispensable catalyst…the sole military coercive instrument.”[31]

In the latter half of the campaign, NATO leaders and their air strategists applied air weapons toward positive strategic objectives. They destroyed an array of interconnected valuable targets, depriving the enemy of options and, eventually, of the hope he could prevail. In so doing, NATO leaders and military strategists rescued Operation Allied Force from the mire of gradualism from which it arose. Despite its inauspicious beginnings, the air campaign achieved its objectives in a remarkable 78 days.

Conclusion

Twenty years after Allied Force, the student of history finds that the precise application of air power continues to increase air power’s military and political utility, and that strategists must logically link positive military objectives to desired political outcomes.

The precise, discriminate application of air power has become even more crucial to maintaining the legitimacy of a campaign and the state(s) behind it. Western news networks pioneered real-time war coverage in the 1990s. Today, audiences around the world watch wars live on TV and Twitter. These constant audiences increase the social and political restraints on democracies’ use of force. While the imperative for precision is a restraint upon air power employment, it does not necessarily reduce the leverage air power can generate. In fact, especially for the United States and its allies, the opposite is often true.

As Clausewitz said, “The maximum use of force is in no way incompatible with the simultaneous use of the intellect.”[32] Socio-political demands for precision and target discrimination give the air strategist further incentive to think—to make every sortie and every payload serve a positive military objective, which should in turn contribute to a desired political end state.[33] This is the sort of problem American and allied strategists should want. They should want to be in the business of maximizing leverage, options, and advantage, rather than simple destruction.[34] This schema sets us apart from our adversaries. Air strategists in U.S.-led coalitions from before Allied Force to current conflicts have confronted the tension between destructive air power and values-based restraints.[35] They have employed ever more precise weapons and ever more stringent collateral damage mitigation procedures, often sacrificing military expediency in the pursuit of a more politically-effective grand strategy.

…the need for positive objectives and maximum leverage may seem doctrinal truth, perhaps even self-evident. But for political leaders, these military imperatives often conflict with international, domestic, fiscal, or social pressures…

Allied Force also reminds us that, to contemporary military minds, the need for positive objectives and maximum leverage may seem doctrinal truth, perhaps even self-evident. But for political leaders, these military imperatives often conflict with international, domestic, fiscal, or social pressures—pressures that can inform, focus, or undermine a military strategy, depending upon how they are managed.[36] Clausewitz reminds readers which factors are prime: “The main lines upon which military events progress, and to which they are restricted, are political lines that continue throughout the war to the subsequent peace. How could it be otherwise?”[37] Bearing the primacy of politics in mind, military strategists must discern and articulate clear, positive military objectives that support the desired political end state, while preserving popular support and flexibility for policymakers. The phased air campaign in Allied Force differed from the ideal of American air power employment; nevertheless, the campaign successfully preserved and expanded NATO’s options, while systematically eliminating options for Milosevic.

Michael Trimble is a U.S. Air Force officer and a graduate of the School of Advanced Air and Space Studies. The views expressed in this article are those of the author; they do not necessarily reflect official policies or positions of the U.S. Air Force, Department of Defense, or the U.S. Government.

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Header Image: A F-16 Fighting Falcon flies over Aviano Air Base, Italy, as it departs for an NATO Operation Allied Force mission in the Balkans March 27, 1999. (SrA Mitch Fuqua/USAF Photo)

Notes:

[1] Carl von Clausewitz, On War, ed. and trans. Michael Howard and Peter Paret (Princeton, NJ: Princeton University Press, 1976), 87: “War is not merely an act of policy but a true political instrument, a continuation of political intercourse, carried on with other means.” And, B.H. Liddell Hart, Strategy, 2nd revised ed. (New York: Meridian, 1991), 322: "While the horizon of strategy is bounded by the war, grand strategy looks beyond the war to the subsequent peace."

[2] Liddell Hart, Strategy, 338.

[3] Clausewitz, On War, 88.

[4] Colin S. Gray, in Benjamin S. Lambeth, The Transformation of American Air Power (Ithaca, NY: Cornell University Press, 2000), 7: “All weapons are tactical in their immediate effect and strategic in the consequences of their actions.”

[5] Clausewitz, On War, 76: “If, then, civilized nations do not…devastate cities and countries, it is because intelligence plays a larger part in their methods of warfare and has taught them more effective ways of using force than the crude expression of instinct.”

[6] Susan Hannah Allen and Tiffiny Vincent, “Bombing to Bargain? The Air War for Kosovo,” Foreign Policy Analysis 7, no. 1 (2011): 17-18.

[7] Allen and Vincent, “Bombing to Bargain,” 17-18, points out that in the case of Allied Force, Milosevic’s army did not constitute a strategic center of gravity: “The military was not an important base of his political support…Because NATO’s central demand was political rather than military, damaging Milosevic’s political power was more costly for him than the damage to his military power.” This stands in stark contrast to Robert Pape’s theory in Bombing to Win, and to Clausewitz’s own examples of 19th-century France’s centers of gravity ("The center of gravity of France lies in the armed forces and in Paris.") On War, 633.

[8] B.H. Liddell Hart, Strategy, 2nd revised ed. (New York: Meridian, 1991), 330, 335.

[9] J.C. Slessor, Air Power and Armies (1936; repr., Tuscaloosa, AL: University of Alabama Press, 2009), 4-7.

[10] Major Julian Tolbert, USAF, “Crony Attack,” (master’s thesis, School of Advanced Air and Space Studies, 2006), 41.

[11] Mark Clodfelter, The Limits of Air Power: The American Bombing of North Vietnam (Lincoln, NE: University of Nebraska Press, 2006), xv.

[12] This position builds upon Clodfelter’s work, as well as Colin Gray’s observation that air power is a poor tool for sending diplomatic messages. Colin S. Gray, Air Power for Strategic Effect (Maxwell AFB, AL: Air University Press, 2012), 281.

[13] Dag Henriksen, NATO’s Gamble: Combining Diplomacy and Airpower in the Kosovo Crisis 1998-1999 (Annapolis, MD: Naval Institute Press, 2013), ix-xi, 3-5. Daniel Byman and Matthew Waxman call this crucial, often-overlooked link between military means and desired political ends the “coercive mechanism” in The Dynamics of Coercion: American Foreign Policy and the Limits of Military Might (Cambridge, UK: Cambridge University Press, 2002) 48-50. 

[14] Paul E. Gallis, “Kosovo: Lessons Learned from Operation Allied Force,” CRS Report RL30374, Washington, D.C.: Congressional Research Service, November 1999), 2.

[15] Lambeth, Transformation of American Air Power, 183; and, “Kosovo Air Campaign,” NATO public site, 7 April 2016. https://www.nato.int/cps/en/natolive/topics_49602.htm?

[16] Henriksen, NATO’s Gamble, 7, 11, 138, 140.

[17] Lambeth, Transformation of American Air Power, 184; and, Henriksen, NATO’s Gamble, 86.

[18] Mason, “Operation Allied Force,” 237, on Belgrade’s ambiguous reactions to the bombing; Stephen T. Hosmer, The Conflict over Kosovo: Why Milosevic Decided to Settle When He Did (Santa Monica, CA: RAND Corporation, 2006), 19, 21; Earl H. Tilford, Jr., “Operation Allied Force and the Role of Air Power,” Parameters 29, no. 4 (Winter 1999-2000), 24-38.

[19] Air Vice Marshal (Ret.) Tony Mason, Royal Air Force, “Operation Allied Force, 1999,” in A History of Air Warfare, ed. John Andreas Olsen (Dulles, VA: Potomac Books, 2010), 232.

[20] Lambeth, Transformation of American Air Power, 184-186.

[21] Lambeth, Transformation of American Air Power, 184.

[22] Mason, “Operation Allied Force, 1999,” 234-235. This practice of exploiting Western powers’ observance of LOAC, now prevalent among U.S. and NATO adversaries, has been called “compliance-leverage disparity.” See Orde F. Kittrie, Lawfare: Law as a Weapon of War (Oxford: Oxford University Press, 2016), 11-12, 18-25.

[23] Lambeth, Transformation of American Air Power, 186.

[24] Lambeth, Transformation of American Air Power, 187. The escalated campaign seems to have drawn upon Col John Warden’s “Five Rings” theory for air power employment, which advocated attacking the enemy from the inside out by striking (in order of primacy): the enemy’s leadership, essential production (fuel, power, etc.), infrastructure, population, and fielded forces. For a concise summary of Warden’s Five Rings, see John Andreas Olsen, Strategic Airpower in Desert Storm (London: Routledge, 2003), 83-85.

[25] Tolbert, “Crony Attack,” 31-35.

[26] Lambeth reports the use of a bunker-busting precision-guided bomb against a national command center, cruise missiles against political party offices, and cluster munitions against Belgrade’s major power relays. Lambeth, Transformation of American Air Power, 187-188. Thomas Schelling explained one must know “what an adversary treasures” in order to coerce the adversary using military force. Thomas Schelling, Arms and Influence, new ed. (New Haven, CT: Yale University Press, 2008), 3.

[27] Lambeth, Transformation of American Air Power, 186-189.

[28] General Michael Ryan, U.S. Air Force Chief of Staff, in Mason, “Operation Allied Force, 1999,” 248.

[29] Lambeth, Transformation of American Air Power, 187-193; Cooper, “Air Power,” 8-9; Allen and Vincent, “Bombing to Bargain,” 22; Tolbert, “Crony Attack,” v, 28, 35-38.

[30] Byman and Waxman, Dynamics of Coercion, 48-50 (on coercive mechanisms).

[31] Mason, “Operation Allied Force, 1999,” 244.

[32] Clausewitz, On War, 75.

[33] Colin S. Gray, in Benjamin S. Lambeth, The Transformation of American Air Power (Ithaca, NY: Cornell University Press, 2000), 7: “All weapons are tactical in their immediate effect and strategic in the consequences of their actions.”

[34] Clausewitz, On War, 76: “If, then, civilized nations do not…devastate cities and countries, it is because intelligence plays a larger part in their methods of warfare and has taught them more effective ways of using force than the crude expression of instinct.”

[35] Lambeth, Transformation of American Air Power, 204-206; and, Bradley Jay Strawser, ed., Killing by Remote Control: The Ethics of an Unmanned Military (Oxford: Oxford University Press, 2013), 152-153, 176; and, Hon Heather Wilson, Secretary of the Air Force, “Air Force Secretary: The Law of War and the Power of Computing,” National Interest, 4 September 2018.  

[36] JP 5-0, Joint Planning, IV-21, GL-11, I-10.

[37] Clausewitz, On War, 605.