Why Military Force Matters

Is the use of force a defensible foreign policy tool and, if so, when and why? There are two main arguments against the use of force, either in specific instances or as a more general policy. The first is pragmatic. Are the goals of the use of force vital to America’s national security? If so, are these goals important enough to justify the likely costs in terms of American lives and treasure? And if they are, can policymakers be relatively confident the use of force will achieve their aims, without unintended and destructive consequences beyond the immediate military objective? These are serious questions, to which we shall return.

The second major argument against the use of force is a moral one. This argument holds that the United States has no legitimate basis to intervene in the affairs of other nations, including nations ruled by tyrants. This argument offers clear-cut operational guidance: It is wrong for the United States to intervene abroad with force. And by implication, nonintervention is the morally sound choice.

Though clear-cut, this latter argument is so simple as to be simple-minded. Was American nonintervention in the Rwandan genocide of 1994 a moral policy? More than 700,000 Rwandans were hacked, burned, or otherwise tortured to death and more than two million others were displaced. If the United States could have prevented most of these deaths at little cost in American lives and dollars, would this not have been a legitimate, moral use of military force? Bill Clinton later said his failure to respond to this genocide was one of his presidency’s greatest failings. He said that intervention could not have prevented the violence but could have reduced it substantially. Of his choice not to intervene, he later concluded, “I regret it.”

There might have been solid pragmatic reasons to stay out of Rwanda. Occurring only a handful of years after the demise of the Soviet Union, the Rwandan genocide offered an early case in which local instability had no larger geo-political implications. During the Cold War, every instance of violence or instability was seen through a zero-sum lens: If the United States did not intervene, a fertile field was opened up for Soviet expansion. Why, in this new world, should Washington risk even one life or one dollar? Why risk another Somalia-like disaster if there is no American cost to inaction? Though it is hard to find any moral grounds on which to defend President Clinton’s inaction, these practical considerations remain a matter of judgment.

Much the same could be said today about President Obama’s policy toward Syria. There might well be good practical reasons not to get caught up in a complex military intervention in Syria. But moral grounds for declining to do so are not among them. Upwards of 470,000 Syrians have been killed in the last five years and millions have been displaced to often squalid refugee camps or fled the region for Europe. Generations of Syrians will suffer the consequences of nonintervention by Western forces. American military engagement in Syria is fraught with far more difficulties than Rwanda, and differing degrees of engagement must be weighed carefully in light of American interests. But among these considerations it is hard to find a superior moral orientation.

The United States often has solid pragmatic reasons not to intervene in the affairs of other nations, but moral grounds are seldom among them. Indeed, it is from the moral deficiency of absolute nonintervention that the “responsibility to protect” doctrine evolved. The U.N. World Summit Outcome Document, agreed to in 2005 by U.N. members including the United States, specifies that peaceful means to address genocide and other crimes against humanity must first be employed. But if these means are not successful, members have not only a right but an affirmative responsibility to use military force to protect people against these grave crimes. Whatever one might make of this doctrine (it is unlikely to replace pragmatic considerations about using force), it demonstrates that belief in the moral superiority of certain uses of force is not confined to overly hawkish neoconservatives but finds resonance across the international political spectrum.

Pragmatic Arguments

Abstract theorizing provides less concrete guidance than an evaluation of the successes and failures of the use of force in recent history. Let’s consider the period from the end of direct U.S. military involvement in Vietnam in 1973 to the present. The lengthy and ultimately unsuccessful American involvement in Vietnam caused deep national soul-searching about the use of force. The loss of more than 58,000 American lives spoke to the need for great caution in undertaking costly, large-scale military involvement in the affairs of other nations; it informs policymakers’ thinking to this day.

Moreover, in 1973 Congress enacted the War Powers Resolution (WPR). This legislation codified the congressional hope that future uses of force would be determined by the collective judgment of the president and Congress. Though all presidents have regarded portions of the WPR as unconstitutional, the Supreme Court has never ruled on this (and is unlikely ever to do so), and it remains the law of the land. Finally, no post-Vietnam conflict has seen combat by American conscripts. The all-volunteer military exercises a subtle, but marked effect on U.S. decisions to employ force.

So what does the contemporary American way of war look like? In the 43 years since 1973, presidents have notified Congress (“consistent with the WPR”) of the deployment of U.S. forces no fewer than 187 times. Granted, many were pro forma notifications concerning alterations to the U.S. force structure in ongoing conflicts rather than discrete events. On the other hand, these 187 deployments do not include U.S. covert operations or routine training or stationing of forward-based U.S. troops.

The vast majority of these deployments were undertaken to evacuate U.S. citizens from danger; provide additional security to embassies abroad; transport allied forces engaged in humanitarian or rescue missions; provide security for humanitarian relief efforts; or provide intelligence, logistical support, and training for friendly foreign forces. Of the 187 U.S. force deployments since 1973, most have been relatively brief, exposed U.S. forces to limited risks, prompted (with exceptions) little or no congression-al concern, and have been widely supported. Most of these operations have not been opposed by even the most isolationist critics. These uses of force, initiated entirely by presidents, by the way, are likely to remain uncontroversial and to continue under any future president.

The more interesting cases, of course, are the substantial uses of military force, cases in which Congress has invoked, or at least considered invoking, the WPR. Twelve such instances provide a solid set of cases for evaluating the use of force since 1973. In only two of these cases—both relatively minor in scope and occurring more than two decades ago—was the use of military force clearly a failure. In the other 10 cases military force was successful in achieving its intended goals; the costs justified the use of force; and problems that arose were not the result of the application of military force but the result of either the insufficient application of force or of a mistaken set of assumptions that had little to do with the use of force itself.

Two Failures

Two cases resulted in failure. The first was the deployment of U.S. Marines to Beirut by President Reagan. By August of 1982, Lebanon had descended into sectarian violence, and U.S. troops were deployed as part of a multilateral peacekeeping force to oversee the evacuation of PLO forces and to preserve order. When this mission was accomplished, U.S. forces were withdrawn in September—only to return within the month.

Marines came under hostile fire during their second deployment in late 1982 and 1983. President Reagan sent three reports to Congress, though none mentioned hostilities that would arguably have triggered the termination clause of the WPR. At that time, Congress was eager to defend its prerogatives and intended to trigger the WPR when significant hostilities first occurred. The president and Congress negotiated an understanding: Congress passed and President Reagan signed legislation stating that the WPR had gone into effect on August 29, 1983, but authorizing the U.S. troop presence in Lebanon beyond 60 days for a full 18 months. In signing this first-ever invocation of the WPR, President Reagan stated that nothing within it detracted from his constitutional powers as commander in chief.

On October 23, 1983, U.S. Marine barracks near Beirut International Airport were attacked with a massive truck bomb, killing 241 servicemen. After several months of sporadic responses, on February 7, 1984, President Reagan ordered a withdrawal of U.S. forces, which was completed more than a year before the 18-month authorization was to expire.

Although the motivation for deploying U.S. troops was admirable, the mission itself was fraught with problems. It was open-ended, with no specific goal in sight. There was no peace to be kept, so the peacekeeping moniker itself was misleading. The Marines were positioned dangerously, especially after unfriendly forces took control of surrounding hills, and the rules of engagement were poorly thought through.

In short, the goal of U.S. intervention was vague, the operation did not justify the toll of American lives, and it is hard to discern any measure by which this operation could be called anything but a failure.

A second failure occurred a decade later. President George H. W. Bush sent U.S. military forces to Somalia to protect U.N. personnel delivering food to starving Somalis. President Bush acted under a U.N. Security Council resolution, and he reported the deployment of American forces to Congress on December 10, 1992. In his report, he noted that hostilities were not expected, making clear his view that this action would not trigger the WPR. This mission continued until May 1993, successfully delivering food in massive quantities. Violence was minimal and as many as an estimated 100,000 Somali lives were saved.

Based on this success, the U.N. passed a resolution broadening the scope of the mission considerably. U.N. forces were now to aim for a reconciliation of warring parties in Somalia; factions were to be disarmed, infrastructure was to be repaired, and Somalia was to be set on a course toward democratic government. These nation-building missions were actively supported by President Clinton, who had been inaugurated four months earlier, though U.S. force levels were drastically reduced at the very time the scope of the mission expanded.

Somali leaders like Mohammed Farah Aidid, who had had no objection to food deliveries, resisted the growing U.N. takeover of local power centers. In June 1993, 24 Pakistani peacekeepers were killed by Aidid’s forces and the United States ramped up efforts to hunt down Aidid. Numerous clashes occurred, including a bombing that killed four Americans. On October 3, 18 U.S. servicemen were killed in Mogadishu, an event later memorialized in the movie Black Hawk Down.

Throughout the period of escalating violence, Congress was unable to come to agreement about the WPR. On February 4, 1993, the Senate authorized the use of force in Somalia, and the House subsequently adopted a conditional authorization. The two chambers, however, did not reconcile their legislation, and the WPR was never invoked. Four days after the death of the 18 servicemen President Clinton announced the end of combat operations and his intent to withdraw U.S. forces no later than March 31, 1994. Congress adopted this date in legislation that cut off funding for U.S. forces in Somalia. All U.S. forces were withdrawn from Somalia in advance of this date.

Though the initial deployment of U.S. forces was successful in preventing a far-reaching humanitarian disaster, the expanded U.N. mission was not. The scope of the wider mission was not thought through, and the mismatch of a smaller U.S. footprint with a much wider mission made no sense. American expectations of widespread Somali gratitude were unmet, an experience repeated later in Iraq. The mission was ill-defined, not a vital national security interest, and failed to achieve any of its stated goals. Somalia today is no better for it, and it is hard to judge this operation as anything but an abject failure.

Six Successes

Other uses of U.S. military force have been far more successful. Consider the invasion of Grenada ordered by President Reagan in the fall of 1983. Grenada had descended into chaos after an internal struggle among its Marxist leaders led to the assassination of Prime Minister Maurice Bishop. Fearing the consolidation of power under hardline Marxist Bernard Coard, Reagan ordered 7,600 U.S. troops to invade Grenada on October 25.

Left unchecked, Grenada was rapidly becoming an ally of Soviet proxies. The small island hosted more than 700 armed Cubans, some of whom were constructing an airport suitable for heavy military aircraft. The prospect of a second Soviet beachhead in the Caribbean ran directly against the national security interests of the United States. The American invasion was intended to establish a new interim government in Grenada leading to democratic elections—which is exactly what occurred. Fighting ended within several days, with 19 U.S. servicemen killed. The invasion was broadly supported by the American people and, as polls revealed, by the Grenadian people as well.

President Reagan reported to Congress, consistent with the WPR, but without reference to the section that would trigger the 60-day termination feature. The House and Senate quickly passed bills fixing the beginning of the 60-day period on October 25. These bills, however, were never reconciled and sent to the president. For his part, President Reagan committed to removing U.S. combat forces from Grenada within 60 days, which was completed by December 15.

The Grenada invasion was the first rollback of a Communist government by military force. Though the invasion was opposed by the president’s friend and ally Margaret Thatcher and by a U.N. General Assembly vote of 108-9, no lasting diplomatic damage was done. Grenada established a democratic government, and Soviet influence in the Caribbean was diminished.

Six years later, the United States used military force in Panama to remove Manuel Noriega from power. Noriega had a longstanding relationship with U.S. government agencies, but that relationship began to fray as he used his office to support hemispheric drug trafficking. When pressured by the United States, which maintained a permanent military force in the Canal Zone, Noriega warmed increasingly to Cuba and Nicaragua. In 1989 he overturned the legitimate election of Guillermo Endara as president in order to retain power. Acting on behalf of Noriega, the Panamanian legislature declared war on the United States. Then several U.S. servicemembers were killed in an incident provoked by Noriega’s forces.

President Bush responded on December 20, 1989, with an invasion force of 27,000 troops. Fighting ended within days. Twenty-three Americans were killed; Noriega surrendered to U.S. forces on January 3 and was deported to the United States to stand trial on drug-related charges. President Bush reported the use of force to Congress on December 21. Congress had gone out on recess on November 22 and did not return until January 23, shortly before the last U.S. combat forces were withdrawn from Panama. Once again, Congress took no action with regard to the WPR.

Endara became the president of Panama, and Panama subsequently enjoyed successive rounds of free elections and the transfer of power between political parties. Though the U.N. General Assembly opposed the invasion by a vote of 75-20, polls suggested most Panamanians supported the U.S. action, which was also highly favored by the American public. The invasion achieved the goals of protecting American citizens in Panama, ensuring the security of the canal, ending a government-run drug cartel, and restoring democratic government to Panama.

President Bush was to deploy a far more massive military force less than a year later. In August 1990, Iraq’s Saddam Hussein invaded and quickly took control of neighboring Kuwait. The United States had maintained a complicated relationship with Saddam Hussein for many years, though that relationship became increasingly difficult following the end of the Iran-Iraq war. In response to Saddam’s invasion of Kuwait, President Bush sent 200,000 American troops to Saudi Arabia and supplemented that force by 150,000 several months later. He notified Congress on both occasions, though noting that the deployments were for defensive purposes. Saudi leaders were deeply concerned that Saddam might take control of oil fields that were in striking distance of his forces.

The U.N. Security Council passed Resolution 678, demanding that Iraqi forces withdraw from Kuwait no later than January 15, 1991, and authorizing U.N. members to use “all necessary means” to secure that outcome. President Bush argued that he did not need congressional authorization to use force against Iraq, though he welcomed what he called a congressional vote of “support.” The House and Senate, consistent with the requirement of the WPR, passed legislation to authorize the use of force against Iraq, which was signed by President Bush. Following an air campaign of several weeks, U.S. forces invaded Iraq and within four days decisively defeated Iraqi forces and freed Kuwait. There were 148 American battle-related deaths.

Tactically, the war was a great success. It also secured the larger goals of American foreign policy: removing Iraq from Kuwait, affirming the idea that conquest of neighbors was unacceptable, and securing vital Saudi oil production facilities. Following the American withdrawal from Iraq, the United States enforced a U.N. mandate to restrain Saddam’s forces, largely by establishing no-fly zones in the north and south of Iraq. These enforcement actions were motivated less by military requirements than by humanitarian concerns about Shiite and Kurdish populations in Iraq.

Early in the Clinton administration a disintegrating Yugoslavia spiraled out of control. Was it in the U.S. national security interest to intervene in a struggle among the Croatians, the Bosnians, and the Serbians? Why not let the situation unfold on its own, or at least let other European nations deal with a problem on their own continent? Apart from the humanitarian dimension of the conflict, this was the first post-World War II use of violence to rearrange boundaries on the European continent. Twice before in the 20th century, the United States had been drawn into major European conflicts. United States policymakers saw a significant interest in setting out a clear marker against the use of force in Europe. The goal of a Europe whole, free, and at peace was a national interest of the United States.

In the complex series of U.N. peacekeeping missions in the former Yugoslavia between 1992-1995 and afterward, the United States military played a variety of roles including delivering supplies, enforcing a no-fly zone against Serb forces, and serving on the ground as peacekeepers. In all, Presidents Bush and Clinton notified Congress of changes in U.S. troop deployments in the region no fewer than 27 times. For its part, Congress produced a series of contradictory votes for and against these actions, in support of the troops, and against the insertion of U.S. ground forces. Overall, Congress seemed relatively content to allow President Clinton to use air assets as he wished, but sought to authorize in advance any deployment of ground forces.

Following the Dayton Agreement between the warring parties in December 1995, President Clinton sent more than 30,000 U.S. troops to the region—without congressional authorization. Because these troops were part of a NATO-led force, designed to secure what looked like a genuine peace, Congress lost its initial inclination to authorize the use of ground forces. Despite nearly five years of air patrols, airstrikes, aerial combat, and the deployment of U.S. ground troops, Congress once again never invoked the WPR.

Throughout its actions during these years, the United States suffered only one fatality. Peace was secured and leadership of the peacekeeping operation was passed to European nations. The military deployment was a tactical success, and the overall policy goals were achieved at relatively little cost.

In Haiti, a military coup led by General Raoul Cédras ousted the democratically elected president, Jean-Bertrand Aristide. Under pressure from the United States and other nations, in July 1993 Cédras and Aristide reached an agreement to permit Aristide to return to power. President Clinton dispatched 350 American troops to Haiti to reinforce this understanding, stating that no hostilities were expected. A U.S. Navy ship arriving on October 11, however, encountered resistance, and it appeared the agreement to allow the return of Aristide had fallen apart. In response, the U.N. Security Council voted for an embargo against Haiti. Congress adopted a nonbinding “sense of the Congress” resolution that no funds could be used for military action in Haiti without prior congressional authorization. Despite this, President Clinton chose to enforce the embargo.

The Security Council then raised the ante, authorizing “all necessary means” to remove Haiti’s military government. President Clinton prepared to invade Haiti. He said he would welcome a congressional vote of “support” but that he did not require authorization to proceed.

The invasion was called off when a U.S. negotiating team secured agreement from General Cédras to step down. President Clinton then deployed U.S. forces in Haiti not as combatants but to enforce this agreement. President Clinton ultimately deployed 21,000 U.S. forces to Haiti. Several minor skirmishes took place but no significant violence. Congress did not invoke the WPR. It did, however, pass a resolution stating that the president “should have” requested congressional authorization and calling for the “prompt withdrawal” of U.S. forces.

The United States suffered one military fatality in its multiyear deployment in Haiti. The threat of force (which was no bluff in this instance) achieved its immediate goal. This was not a nation-building exercise; it aimed only to restore the deposed president. The goal of returning democratic rule to Haiti was achieved.

In 1998 parties in the former Yugoslavia again went to war. The Kosovo Liberation Army and the Serb-run Federal Republic of Yugoslavia engaged in intense fighting, replete with mass atrocities, especially on the Serbian side. President Clinton said in June that this situation was an “unusual and extraordinary threat to the national security and foreign policy of the United States.” Was it? Aside from significant humanitarian concerns, there was once again the prospect of violence to settle disputes on the continent of Europe. In response, NATO-led forces including the United States conducted bombing missions against the Serbs from March 24 through June 10, 1999.

Both sides agreed to a negotiated cessation of violence and the deployment of U.N. peacekeepers. Under a Security Council resolution, a NATO-led force (KFOR) was deployed to Kosovo. The goal was to move Serb forces out of Kosovo, bring in peacekeepers, and disband the Kosovo Liberation Army. A total of 39 countries provided 50,000 peacekeeping troops, including 7,000 from the United States. A total of 168 coalition lives were lost including 18 Americans, only 4 of which occurred in hostile encounters.

President Clinton and his successors reported 12 times to Congress on the deployment of U.S. forces to Kosovo, and an additional 16 times as part of broader reports on the worldwide deployment of U.S. forces. Though Congress seemed once again to oppose the introduction of U.S. ground forces without prior congressional authorization, Congress did not invoke the WPR.

KFOR troops including the American contingent accomplished their goal of ending the violence between Serbs and the KLA. Serb forces—and many Serb civilians as well—left Kosovo and hundreds of thousands of Kosovar refugees returned.

Two Hard Cases

Afghanistan and Iraq offer much harder cases. The length of these conflicts is nearly unprecedented in American history. The Afghan deployment is now in its 15th year, making it the longest-running war in American history. The deployment in Iraq lasted from 2003 to 2011 and has recently ramped up again. The loss of life in these two wars has been far greater than in all other post-Vietnam conflicts combined. The goals of both conflicts widened over the years to encompass broad-scale nation-building that was not envisioned in the original decision to go to war. Finally, and importantly, the outcome in both cases remains uncertain. It is not clear, for example, that the current Afghan government would outlast a U.S. departure by even a month. And in Iraq the long-term relationship between Sunni, Shiite, and Kurdish populations is still a work in progress.

Following the 9/11 attack, the United States demanded that the Taliban government of Afghanistan turn over the perpetrators of 9/11 and close terror training camps. When these demands were rejected, the United States invaded Afghanistan to hunt down the perpetrators and replace the regime that gave them sanctuary. The CIA- and military-led effort quickly carried out these limited objectives. Within two months, the Taliban government had been driven from Kabul and planning was underway to install Hamid Karzai as interim president. American fatalities in the early years of the Afghan conflict were surprisingly low—7 in 2001, 30 in 2002, and 33 in 2003.

Given the Taliban’s refusal to cooperate, the use of military force was more or less inevitable. Not to respond to the murder of more than 3,000 civilians on 9/11 would have been unthinkable. As evidence of this, the congressional authorization to use military force against those directly and indirectly responsible for 9/11 was passed 420-1 in the House and 98-0 in the Senate.

Had the United States chosen to withdraw from Afghanistan after putting Karzai in place, the war would have been brief and casualties minimal—but Afghanistan would have quickly descended into chaos and likely seen a speedy return to power of the Taliban. Indeed, the Taliban insurgency had already ramped up by late 2002, leading to the first of several U.S. troop surges to counteract it.

Here Washington faced a dilemma, much the same as it did soon afterward in Iraq and again more recently in Libya. To leave without setting in place the conditions for a stable post-Taliban government would have struck a blow against the 9/11 perpetrators but fundamentally changed nothing in Afghanistan. Was this a desirable outcome? Would it have been preferable to do as we later did in Libya, helping to oust Qaddafi but then leaving the country to its own devices?

Staying on indefinitely was understandable, as one incremental decision led to the next, but it was not a necessary or inevitable result of the quick U.S. military victory. Most of the 2,380 American deaths in Afghanistan occurred many years after the 2001 invasion; in the four years of the first Obama administration, from 2009-2012, more than 1,500 U.S. servicemembers were killed. In 2009 General Stanley McChrystal estimated that defeating the Taliban would take a multiyear commitment of as many as 240,000 Afghan soldiers, 160,000 Afghan police, and an increase of at least 30,000 U.S. forces to supplement the 68,000 already there. Today the United States maintains 9,800 troops (and 26,000 military contractors) in Afghanistan, a force that is obviously inadequate to defeat the Taliban insurgency. One might fairly ask what U.S. troops are accomplishing in Afghanistan today, beyond buying enough time for Barack Obama to pass this problem along to his successor.

The initial military attack on Afghanistan was tactically brilliant and accomplished its immediate aims at low cost. The U.S. experience in Afghanistan since 2003 has proven how difficult and time-consuming it is to construct a new Afghanistan. Building a new nation in the midst of an ongoing insurgency is a nearly impossible task.

We have experienced much the same in Iraq. The use of force to remove Saddam Hussein from power was remarkably quick and efficient. The American bombing campaign began on March 20, 2003, and by April 9 Baghdad had fallen to American forces. Tikrit, the last significant holdout, was subdued on April 13. In the month or so after the invasion, 139 U.S. military service personnel were killed. From a tactical standpoint, the conquest of a nation the size of Iraq and the removal of its government so quickly was an indisputable success.

But why did the invasion occur in the first place? The Iraq war has served as Exhibit A for critics of the use of American force; it has been called a “war of choice,” unrelated to U.S. national security interests. Is this true? The pros and cons of this question have been dealt with extensively elsewhere. Saddam Hussein had regularly—increasingly—violated U.N. resolutions establishing no-fly zones to protect elements of the Iraqi population. In response, President Clinton had struck Iraqi targets more than 130 times during his administration. Saddam Hussein had also prevented U.N. inspectors from examining sites suspected of producing weapons of mass destruction. And he had engaged in systematic human rights violations against Iraqis.

Were these sufficient grounds for going to war? There was certainly plenty of agreement to do so. The war was conducted to enforce U.N. Security Council resolutions. The war was fought by troops from dozens of nations. Congress voted heavily in favor of it, the House 296-133 and the Senate 77-23. Interestingly, congressional support for the war, which included senators Hillary Clinton, Joe Biden, and John Kerry, was far stronger than the 1991 authorization of the Gulf war, where the House voted in favor 250-183 and the Senate 52-47.

It is easy enough to point to post-invasion mistakes. Given Iraq’s longstanding culture of absolute rule from the center, it was difficult to get ordinary Iraqis to assume responsibility for anything. Policymakers overestimated the degree to which Iraqis would welcome U.S. control of Iraq, even if only temporarily. It should perhaps not have been surprising that Sunnis accustomed to running the country would resent their demotion. This problem was magnified by the mistaken decision to fully de-Baathify the new government, causing roughly 100,000 Iraqis who might have helped to stabilize and remake Iraq to lose their jobs. This decision exacerbated already deep fissures between Sunnis, Shiites, and Kurds, which came to the fore once they were no longer suppressed by Saddam Hussein’s brutality. But these errors speak less to the decision to use military force than to decisions made once it succeeded.

Moreover—and this is seldom noted—the Afghan and Iraq wars deserve a degree of credit for several positive developments elsewhere. Iran at least briefly moderated its nuclear weapons development program and, more decisively, Muammar Qaddafi gave up entirely his chemical weapons program and moved to align himself with the United States. Having seen how quickly the U.S. military could topple regimes in the neighborhood, neither wanted to offer any unnecessary provocations.

U.S. casualties in Iraq occurred largely after the invasion was complete. The great preponderance of America’s 4,486 military deaths occurred while trying to stand up a stable government in Baghdad, mediate sectarian conflicts, pacify the countryside, ramp up oil production, and return Iraq to a “normal” state. More than 3,400 American lives were lost between 2004-2007.

The decision to stay on in Iraq beyond 2003 was understandable, each incremental decision building upon the last. But the commitment to stay well beyond the successful military invasion was not implied in the invasion itself. General Tommy Franks had outlined a list of objectives in the Iraq war that included removing Saddam’s regime, eliminating any weapons of mass destruction, removing any terrorists, providing humanitarian relief, ending the embargo, protecting the oil fields, and establishing the conditions for a representative government. Most of these goals were accomplished by the invasion itself. It was the last one—establishing the conditions for a stable, functioning representative government—that detained the United States for many years beyond 2003.

There were always reasons to be more hopeful about Iraq than Afghanistan. Iraq was far more developed economically. Moreover, vast Iraqi oil reserves were capable of generating the money to fund a central government and large-scale economic development programs. This is an advantage that Afghanistan simply does not have. Finally, while it is easy to point to the many costs of the Iraq war, these should be balanced not against an alternative of perfection but against the many possible bad scenarios had Saddam Hussein remained in power.

To further prove the utility of military force, we have only to look at the troop surge in 2007. The U.S. military was able to create improved conditions of stability and far lower sectarian violence. The reversion to sectarian violence that occurred with the rise of ISIS in 2013 arose not from the application of military force but from its insufficient and too brief application. Staying in Iraq for eight years after the invasion was not foreordained. But once made, the decision to achieve a stable representative government argued for a commitment to stay long enough to succeed.

Still Unfolding

In March of 2011, U.S. naval and air forces joined in enforcing a naval embargo and no-fly zone against Libya. What was America’s interest in sending U.S. forces into harm’s way in Libya? One could make a case that Libyan ruler Muammar Qaddafi had changed his spots by 2011. Qaddafi had evolved from active terrorism against American forces and civilian airliners to working more closely with the United States. He was one of the first world leaders to denounce the 9/11 attacks. He agreed to eliminate his entire stockpile of chemical weapons (and followed through). By 2007 the United States and Libya were moving toward reconciliation including diplomatic relations, a new American embassy in Tripoli, and the exchange of ambassadors, a process delayed only by legal claims related to the bombing of Pan Am 103 over Lockerbie, Scotland, in 1988.

Why would the United States attack Qaddafi in 2011? What was America’s interest? The main reason offered by President Obama was humanitarian: Qaddafi’s forces were approaching Benghazi to put down opposition forces, and there was fear of a bloodbath. Although President Obama referred to American national security interests, his argument for intervention spoke more about ideals than interests, specifically pointing to the urgent responsibility to prevent the slaughter of thousands of Libyans.

The United States acted in support of a U.N. Security Council resolution calling for “all necessary measures to protect civilians” and participated as a member of NATO implementation forces. NATO forces were successful in preventing a bloodbath in Benghazi and—though never stated explicitly as a U.N. goal—in removing Qaddafi from power. The military campaign lasted from March to October of 2011, when Qaddafi was killed by Libyans. The U.N. mandate expired on October 31, 2011. In the course of this six-month campaign, no Americans were killed. The United States spent roughly $1 billion.

Once again, Congress was unwilling to assert its prerogative in a situation where no U.S. ground forces were involved. Though the military campaign lasted a full six months, Congress never invoked the WPR and President Obama acted without congressional authorization.

Was this military deployment a success? Tactically, yes. However, post-conflict Libya illustrates what happens when, unlike in Afghanistan and Iraq, a dictator is toppled and his country is left more or less to its own devices. With no Western forces in post-Qaddafi Libya, the country descended into chaos and violence from which it has not yet emerged. The death of Ambassador Chris Stevens and three other Americans in Benghazi was one of the fruits of this chaos and, if anything, pointed to the need for not less, but more military force in the aftermath of the conflict. Another fruit of the absence of Western forces was the rise of ISIS in ungoverned areas of Libya. If one were to judge the outcome of the Libyan conflict today, it would be mixed at best. Potential large-scale violence has been replaced by ongoing lower levels of violence and by the emergence of ISIS terror cells.

A more hopeful view, however, is possible. U.S.-backed Libyan government forces are closing in on ISIS in Libya. If the emerging Libyan government is able to eliminate ISIS, restore order, and govern with a degree of stability and moderation, it may yet be possible to say that the Libya campaign was successful in terms of both American interests and American ideals. But it is worth noting that this favorable outcome once again depends very much on the use of American military force, this time to support the Libyan government against ISIS.

Today the United States is using military force in many locations beyond Libya, including Somalia, Yemen, and Pakistan. By far the most extensive use of force is against ISIS in Iraq and Syria. Coalition forces have conducted more than 13,000 airstrikes since August 2014. The national interest in defeating ISIS seems generally accepted: The unparalleled barbarism of ISIS, its destabilization of the Mideast, the worldwide reach of its claims, and its ability to motivate terror attacks in America and elsewhere provide readily understandable reasons. The question is not so much why as how to address the problem of ISIS.

American airstrikes in support of Iraqi, Kurdish, and other ground forces have had a positive effect; ISIS has lost about half its territory in Iraq and 20 percent of its territory in Syria. But so long as ISIS holds population centers like Mosul and Raqqa from which it can work safely, shrinkage of ISIS-held territory around the fringes will not make a significant difference. There is no way to bring an end to the multiple threats ISIS poses other than dismantling its control of these urban areas and eliminating any sanctuary for the group. This will be difficult, it will be costly, and it will require a change in the American configuration of forces.

In this regard the Obama administration has recently expanded the American troop presence in Iraq and is working ever more closely—and ever closer to the front lines—with Iraqi and Kurdish forces. These incremental steps are likely to be only the first such steps required to destroy ISIS in Iraq and Syria.

Though the United States has used force against ISIS for a full two years, Congress has not invoked the WPR. This is despite the fact that the Obama administration is not only using stand-off weapons from the air and the sea, but has deployed American troops on the ground as well. Apparently, the emerging congressional position that it would invoke the WPR only if there are to be “boots on the ground” has been further eviscerated. Ground forces have become more narrowly defined as troops specifically outfitted and configured for combat. As the Obama administration continues to increase ground forces in the region—there are now more than 5,000 U.S. troops in Iraq—Congress is making itself ever more irrelevant.

To eliminate the threat of ISIS to the United States—a threat more real and immediate than in any of the cases we have discussed so far—there is no alternative to military force. We cannot negotiate an end to ISIS, we cannot out-propagandize ISIS, and we cannot persuade our Mideast allies to play a larger combat role without a greater U.S. military presence. A Libya-like solution is not in the cards. The defeat of ISIS is in America’s national interest, and to this end the application of greater military force against ISIS is not only useful but necessary.

Conclusions

What can we conclude? It is certainly not that the use of military force is or should be a first resort. To the contrary, it is the last resort and even referring to the loss of life as a “cost,” as this article has done, can be dehumanizing. The good news is that American presidents do not resort quickly to the use of force. In all the cases we have considered, presidents first sought alternative, diplomatic ways to address the national security threats they encountered. Those who allege that presidents rush to use force are guilty not only of untruth but libel. Anyone familiar with presidential meetings with the families of the fallen, personal notes to these families, or visits with the severely wounded at Walter Reed would know better.

But for all of that, military force has been employed many times since 1973 and most of these times it has been successful. There have been outright failures such as Beirut and Somalia, but the use of force remains an indispensable policy tool.

Second, the notion that the United States uses force unilaterally and without regard to the views of other nations is a canard. Of the 12 cases reviewed here, 11 were prosecuted under U.N. auspices, or with NATO, or with non-NATO allies, or in some cases all three. United States actions in Beirut, Somalia, the Gulf war, Bosnia, Haiti, Kosovo, Afghanistan, and Iraq all enforced U.N. Security Council resolutions. NATO has been deeply involved in Afghanistan, Iraq, Libya, and the fight against ISIS. Even the invasion of Grenada took place with prior agreement from neighboring Caribbean countries. Only the invasion of Panama, where the United States historically maintained a sizable military presence, was a unilateral American action.

Third, it is often said that the American public has become “war weary.” Of exactly what is the American public weary? The burdens and sacrifices of war have fallen entirely on a very small slice of the populace—those who fight in America’s all-volunteer military and their families. What wearies the other 95 percent of Americans? They have not served, they have not sacrificed, and they have not expended a dime in new taxes (the government preferring, as it always does, to borrow the money). Ninety-five percent of Americans could not name a single way in which they have been even modestly inconvenienced by any of America’s post-1973 conflicts.

The casualties of war have fallen entirely on those who serve. To put this in context, in the 43 years since the end of America’s role in Vietnam, in which 58,000 lives were lost, American combat deaths have totaled about 7,500. The average American is 200 times more likely to know someone who has been killed in a traffic accident than in combat abroad. As painful as each of these losses has been, this is hardly the record of a blood-soaked imperial power.

Fourth, there is much to be learned from our long-lasting conflicts, particularly Afghanistan and Iraq. The duration of these wars should instruct us that remaking a nation in an image entirely foreign to its history is not easy. It is far more feasible to rebuild nations (as with the Marshall Plan or certain disaster relief efforts) than it is to build them in the first place. There is no reason to doubt that representative democracy is the best form of government or that freedom, toleration, and economic opportunity are good for all people. But these cannot be achieved in a brief time frame. The United States has kept military forces in Germany, Japan, and Korea for decades. But these troops were not going out on nightly combat-support missions against armed insurgents. Our experiences in Afghanistan, Iraq, and Libya should teach us there is no easy way to build from the outside stable, friendly governments, much less free and prosperous ones. In this regard, we might ask ourselves just what we are hoping to accomplish in Afghanistan in the 15th year that we did not accomplish in the 14th.

Fifth, the record of Congress has been sketchy at best. To its credit, and consistent with the requirement of the War Powers Resolution, Congress authorized the three most extensive uses of force—the Gulf war, Afghanistan, and Iraq. While it is unclear (and a bit of a constitutional nightmare) what might have happened had Congress voted to oppose any of these wars, it is surely preferable to have the president and Congress in agreement regarding major uses of force abroad. With the exception of Beirut in 1983, however, Congress’s role in the other conflicts since 1973 has been dismal. The WPR was designed in part to check presidents but also to compel Congress to step up and take a position on the use of military force. This it has not done.

Technological developments are likely to exacerbate Congress’s irresponsibility. Increasing reliance on drones and other stand-off weapons offers presidents a way to fight wars with minimal casualties. These are precisely the kinds of conflicts with which Congress struggles the most. If Congress is to be involved in any way in decisions to go to war—as the Framers wished it to be—it will require serious thinking about how this can happen. Meanwhile, the case of ISIS remains before us. This conflict will inevitably draw in additional United States forces not only in the air, but on the ground. For Congress to continue to shirk its role here would be a disgrace.

Finally, judgments about the use of force should not assume that inaction is always cost-free. Had George H. W. Bush not driven Saddam Hussein out of Kuwait, who can say what would have occurred? Would Saddam have moved on the Saudi oil fields and cornered a vast share of Mideast oil reserves? The real world never remains static for very long and responsible policymakers must balance the likely costs of action against the likely costs of inaction, however well or little known. Inaction is generally politically safer than action. But to secure American national interests, the use of military force is not always the worst option. Sometimes it is the only option.

Jeff Bergner, author most recently of Against Modern Humanism, served as staff director of the Senate Foreign Relations Committee and assistant secretary of state. He teaches at the University of Virginia.