central aims of the law of war—by tightly concentrating the use of force on its intended targets.
Critics, however, worry that advances in weapons could increase conflict by making war easier to begin. If a nation can simply press a button and destroy a target without risking its own personnel, it will choose a military response more often. United Nations officials give voice to these growing worries. “The expansive use of armed drones by the first States to acquire them, if not challenged, can do structural damage to the cornerstones of international security and set precedents that undermine the protection of life across the globe in the longer term,” declares Christof Heyns, the U.N.’s Special Rapporteur on Extrajudicial, Summary or Arbitrary Executions.13 States can use drones and other technology to launch attacks far from conventional battlefields in ways that escape immediate detection, and perhaps even responsibility. Ultimately, pinpoint strikes will continue to blur any clear line between war and peace.
Whether outside observers applaud or deplore it, technology has driven an evolution of “war” from a clash of national armies on a battlefield to its current, multifaceted, and decentralized forms of conflict. Technology has played a role both in the rise of non-state actors and in helping states formulate responses to these non-conventional security threats. The September 11, 2001 attacks and the evolving sophistication of the Islamic State of Iraq and Syria (ISIS) show that states no longer have a monopoly on armed conflict. These groups have used modern communications, transportation, financial, and social networks to operate across state borders and carry out attacks in the home cities of the West, from Paris and Nice to San Bernardino and Boston. In formulating strategic responses, states have also relied on advanced technology, using high-tech surveillance and strike systems to gain better intelligence and effect precision attacks without the need for large conventional forces. In contrast to the wars of the twentieth century, which concentrated highly destructive forces on discrete battlefields, technology is now dispersing less acutely destructive forces over a broader span. Though technology has contributed to the reach of non-state terrorist groups, it can also assist nations in fighting them.
Cyber warfare, which is even easier to begin and more difficult to prevent, presents yet another form of unconventional conflict driven by technology. Internet attacks can cause real-world destruction and harm, or they can simply interfere with another nation’s communications, financial, or information networks. A cyber attack, for example, could cause a flood by disabling the control mechanisms for a dam or could trigger an explosion by causing a power plant to malfunction. As Russia demonstrated in its invasions of Georgia in 2008 and Ukraine in 2014, nations can also use cyber weapons to support a conventional armed attack.14 Cyber weapons can replace conventional weapons to commit sabotage, as was done through the Stuxnet virus aimed at the Iranian nuclear program. Or governments can use the Internet to steal significant military or intelligence information, such as weapons designs or strategic plans, which appears to be occurring with increasing frequency between the United States and China. “China is using its cyber capabilities to support intelligence collection against the U.S. diplomatic, economic, and defense industrial base sectors that support U.S. national defense programs,” the U.S. Defense Department stated in a 2016 report to Congress.15 “The accesses and skills required for these intrusions are similar to those necessary to conduct cyberattacks.”
In this way, robotics and cyber weapons can exert force that does not necessarily kill or destroy tangible objects, but nonetheless is overtly hostile. Governments and scholars are not always clear about when such attacks meet the legal standards for an armed attack. For example, the new United States Law of War Manual, issued by the Department of Defense in 2015, declares that the existing laws of war should apply to what it calls “cyber operations.”16 But it then concedes that the rules here are “not well-settled” and are “likely to continue to develop.” The United States even takes the position that it may not have a position. The Manual declares that it does not “preclude the [Defense] Department from subsequently changing its interpretation of the law.”17
Indeed, the uncertainty as to how to classify these attacks has played itself out in nations’ inconsistent responses to acts of robotic and cyber warfare. States have sometimes treated them as a form of espionage or covert action, refusing to consider the resulting damage as an act of war. China’s theft of the U.S. Office of Personnel Management database did not prompt U.S. force in response, nor did North Korea’s hacking of Sony’s electronic files. Iran took no overt military action in response to the Stuxnet virus. American drones execute dozens of strikes in countries—such as Yemen, Somalia, Afghanistan, and Pakistan—without sparking any military reaction. And yet, it seems clear that an armed response to such attacks would be appropriate in at least some contexts. Cyber attacks that disable key military command structures or critical civilian networks might very well be regarded as acts of war, along with attacks by robots and drones that kill or injure human beings or destroy property on a large scale.
The rules of war must evolve to keep pace with technology. Some nations demand an inflexible approach to the law of armed conflict because they hope that law can suppress war. Nations with minimal armed forces or weak strategic positions may support legal rules that inhibit other states from asserting potential advantages. Other states may oppose new technologies in the hope of preserving the advantages derived from their current forces. Still others may want to preserve military opportunities for low-tech, asymmetric tactics—those favored by guerrillas, insurgents, and terrorists. Many scholars and international officials may support an inflexible approach to the rules of war from intellectual comfort with the old way of doing things. It is to these problems that we now turn.
Frozen Law in a Changing World
Even as technology advances, legal and political leaders remain reluctant to embrace the use of new weapons. Despite their advantages, these new weapons have become the subject of a broad campaign to limit or even prohibit them. The claim is that these military advances violate the rules governing civilized warfare. Advocates for today’s law of war, known as International Humanitarian Law (IHL) to specialists,18 have used multilateral treaties to construct a set of rules that depart from the realities of modern war. They now hope to freeze into place this new IHL, which tends to favor guerrillas, terrorists, and insurgents over western nations, and conventional ground combat over technology and innovation.
The law of war, however, more appropriately changes through natural evolution rather than artificial codification. They have long depended on the customs and traditions followed by states at war, which have usually decided on regulation after experience with weapons, not before. An evolutionary approach concedes that we do not currently know all the implications of these new weapons. We do not have full information on their characteristics and consequences, or the factual circumstances of their use. Rather than imposing rigid rules, the customary laws of war have usually adopted flexible standards—such as reasonableness in the selection of targets—that allow future decisionmakers to judge the legality of force in their own circumstances. They place more faith in future leaders, commanders, and judges to come to better conclusions in reviewing the use of force after the fact than in the prescience of today’s treatymakers. An approach built on flexible standards allows nations to gather more knowledge about the effects of new weapons, under conditions of deep uncertainty, before reaching fundamental decisions of policy.
In this respect, customary rules on the use of force resemble a common-law standard, such as the classic legal norm of reasonableness. A standard such as reasonableness allows judges to consider the totality of the circumstances before ruling on whether a defendant’s actions were legal. A strict rule, however, such as contributory negligence, imposes a clear norm that reduces liability to a single factor and precludes the influence of later circumstances. Rules reduce decision costs because they are clear and easy to apply, they create legal certainty and predictability, and they require less gathering of information. Rules, however, prevent a nuanced application of law to facts and so often result in inequitable outcomes. Standards demand higher decision costs because of the need for more information and time for consideration. Standards produce greater uncertainty and unpredictability, but they more often produce the better answer. A rule gives more power to the legislators who write the norm earlier and narrow the discretion of future officials, while a standard places more trust in the competence