Ken Watkin on “Drone Warfare: Fighting 21st Century Wars with 1923 Rules”
Today’s post about drone warfare by former Canadian Judge Advocate Ken Watkin could not be more timely. This morning’s New York Times has an excellent front page article (“Drones Define the Deadliest Phase of Ukraine’s War“) reporting that drones are “Cheap, Easy to Build, and Inflicting about 70% of the casualties.”
But what about the law? Ken does a deep dive into existing law related to drones and concludes it “requires modernization.” By bringing his usual superb scholarship to the issue, Ken’s gives this critical – and timely – topic a much-needed analysis.
Drone Warfare: Fighting 21st Century Wars with 1923 Rules
by Kenneth Watkin
Introduction
The use of drones or Unmanned Aerial Systems (UAS) in the Ukraine/Russia conflict highlights the degree to which this means of warfare has come to dominate 21st Century Conflict. The novelty of drones is such that finding common terminology is a challenge. This can be seen in the use of diverse terms such as Unmanned Aircraft (UA), Unmanned Aerial Vehicles (UAV) and Unmanned Combat Aerial Vehicles (UCAV).
Their widescale employment by regular armed forces, as well as organized resistance groups, non-State actors and the special forces units involved in irregular warfare is changing how hostilities are conducted.
Unfortunately, the legal rules governing that use as part of aerial warfare remain largely based on concepts developed in the early 20th Century, long before the technological revolution that created unmanned aircraft.
This post looks at to aspects of the law governing air warfare. First, the need for the law to address the use of drones by resistance movements and belligerents not qualifying for combatant and prisoner of war status. Secondly, given the widescale use of drones that do not resemble traditional aircraft the question is asked whether some drones would be better categorized as missiles or weapons.
Drones, Drones and More Drones
Since 9/11 drones have proven themselves to be a highly effective, if at times controversial, means of conducting operations. The pervasive use of the Predator drone in a permissive post 9/11 counterterrorism/counterinsurgency environment spawned the term “predator porn”. It described the hours of video feed that military and intelligence personnel could watch, which was provided by the persistent unblinking cameras and advanced sensors mounted on aircraft sized unmanned platforms.
Global Hawk
This technology permitted State security forces to loiter over an area of interest accumulating intelligence on possible high value targets (HVTs) and then strike with missiles in “targeted killings”. The Predator was eventually eclipsed by even larger platforms such as the Reaper (20 meter wingspan) and the Global Hawk (40 meter wingspan), which provided an enhanced capability to “spy” on the enemy from untouchable distances and elevations.
Just a decade ago there was a sense that the State use of drones, which came to dominate post-9/11 counterinsurgency and counterterrorism operations, would likely not have application in large scale conventional operations (LSCO). Air superiority would be determined by more traditional manned aircraft and missile defences.
Prediction about the limits of drone warfare have proven mostly to be wrong. Further, the State monopoly on drone warfare has disappeared. Within fifteen years after 9/11 reports were increasingly surfacing about non-State actors (e.g. Hezbollah, ISIS, Houthis, Hamas, Iraqi militia groups) relying on a variety of drones for reconnaissance, using smaller one way “suicide” drones that act like cruise missiles or loitering munitions, and adapting commercial quadcopters that could drop grenades on State opponents.
This expanding use of drones by State and non-State actors was the harbinger of a more significant impact on aerial warfare that traditionalists were unlikely to have fully imagined. In 2015 Iran was exposed for “putting military surveillance and attack drones into the sky, including “suicide” aircraft that increase risks for Israel and for U.S. ships in the Persian Gulf”. This capability also contributed to the asymmetric threat posed by non-State actors due to its transfer to Iranian proxies.
It has been suggested that “[c]urrently, over 65 non-state actors are known to possess drones, and the unregulated nature of drone usage suggests that this number will continue to rise unchecked.”The Iranian interest in drones also reinforced once again that contrary to what the term LSCO suggests warfare against peer or near peer actors (i.e. inter-State warfare) is not and never has been entirely conventional in character. As the United States manual FM-03 “Operations” states “[l]arge-scale combat operations often include both conventional and irregular forces on both sides” (p. 1-46).
Not only have drones come to dominate some aspects of conventional operations in the Ukraine/Russia conflict they can provide an effective means of waging irregular warfare when put in the hands of resistance movements, State special forces units operating behind enemy lines, and operatives acting within Russia. Both Russia and Ukraine have relied on drones to an extent that might have appeared to a traditional conventional “warrior” twenty years ago to almost be incomprehensible. The Ukrainian Navy alone has indicated it destroyed 37,000 Russian drones in 2024.
Dr. Molloy
As Oleksandra Molloy notes in her 2024 report Drones in Modern Warfare: Lessons Learnt from the War in Ukraine “[t]he conflict has seen the deployment of the widest array of drone types, from military-grade medium-altitude long-endurance drones, such as Turkish TB2, to loitering munitions such as the US Switchblade, to commercial DJI quadcopters and homemade FPV [First Person View] drones.”
The initial reliance on large drones that resemble traditional aircraft appears to have proven earlier predictions concerning survivability on the conventional battlefield to be correct. Larger drones have been vulnerable to air defence and electronic countermeasures and are expensive to replace (p. 30).
However, “[b]y 2024, the Ministry of Defence of Ukraine had already adopted and operated more than 300 models of UAVs of various types, including reconnaissance drones…strike drones, ‘kamikaze’ drones and loitering munitions” (p. 9). Their roles included “adjusting artillery fire, conducting aerial reconnaissance, maintaining situational awareness, striking enemy targets, mining and de-mining some areas, delivering cargo, and evacuating the wounded” (p. 9).
The integration of drones into conventional operations is such that Ukraine has announced the creation of a “drone line” where they are to be integrated into elite units of the Ground Forces and State Border Guard Units. This initiative is intended “to create a 10-15 kilometer deep kill zone, ensuring that enemy forces cannot move without sustaining heavy losses.” Ultimately, it is a technological solution designed to address a significant manpower disparity in comparison to Russian military resources.
Importantly drone use is not limited to conventional units as was seen in a 2023 attack on Moscow. It is suggested to have been carried out by “partisans” operating in that country. Drones are also used in occupied Ukraine. Evidence of this is found where a “FPV drone attack which destroyed a BUK mobile air defence system took place sixty miles behind Russian lines, far beyond FPV range.” Ukrainian military or intelligence paramilitary special operations forces may be operating in support of the partisans in carrying out such attacks.
This raises the question of whether small organized armed groups, or special forces personnel supporting them now have access to a cheap, readily available and effective “air force”. Having produced 1.5 million drones in the first three quarters of 2024 President Zelensky announced a capability to develop 4 million per year.
A production target has been set to produce at least 30,000 long-range missile-drone hybrids, “which feature turbojet engines as alternatives to cruise missiles.” To facilitate drone use Ukraine has created a separate Unmanned Systems Forces Branch within its armed forces. A step being closely followed by Russia.
1923 Rules of Air Warfare/21st Century Conflict?
So, what is the status of drones under international humanitarian law? How well has that law adapted to the proliferation of drones? Are drones aircraft or missiles? Unfortunately, the rules governing air warfare are not clearly established in treaty law, or as part of customary international law.
An indication of the historic deficiency in regulating aerial combat is found in Hersch Lauterpacht’s 1952 assessment (The Problem of the Revision of the Law of War, 29 Brit. Y.B. Int’l. L. 360, 365-366 (1952)) that even after the extensive use of airpower during World War II “[t]he fact is that in the matter of aerial bombardment there is no rule firmly grounded in the past on which we can place reliance—for aerial bombardment is a new weapon which raises new problems.”
Eventually, the 1977 Additional Protocol I did outline treaty rules governing targeting, including precautions designed to limit collateral civilian casualties and damage. That Protocol does not carve out any exceptions for air warfare. This means the provisions applicable to land warfare apply also to aerial conflict. However, even though 90% of the world’s States are Parties to this Additional Protocol a few militarily significant States are not. This includes the United States, although it appears that country treats the targeting provisions as being reflective of customary legal obligations.
Significant gaps remain since Additional Protocol I does not address issues like the belligerent status of aircraft, or the use of non-military aircraft. Unfortunately, those issues are not definitively addressed elsewhere either. The 2020 United States Air Force manual, The Law of Air, Space, And Cyber Operations admits (p. 55) “[t]here is no settled definition of military aircraft in international law.” Instead, there is a general rule “military aircraft include all aircraft operated by commissioned units of the armed forces of a nation bearing the military markings of that nation, and commanded by a member of the armed forces.” Notably it is acknowledged that military aircraft can be manned or unmanned.
Further “[i]nternational custom regarding national markings on military aircraft was developed to preclude any abuse or confusion as to who exercises control over the aircraft”, although “state practice has not established a requirement for an exclusively military crew.” Problematically, this common interpretation of air law is based on the 1923 Hague Rules on Air Warfare [HRAW]. That draft treaty was not adopted in a legally binding form, although those rules have had considerable impact on the opinions of experts regarding what constituted customary international law.
Substantial international treatment of issues such as the legal status of aircraft and their crews, or the entitlement of military aircraft to exercise belligerent rights did not occur until the development of 1995 San Remo Manual on International Law Applicable to Armed Conflicts at Sea. Reference to air warfare is similarly found in the 2023 Newport Manual on the Law of Naval Warfare. In both cases this was a recognition that aerial operations are part of naval warfare.
A comprehensive non-State explanation of the law governing air warfare had to wait until the development of the 2009 HPCR Manual on International Law Applicable to Air and Missile Warfare and its accompanying 2010 Commentary [hereinafter the Air Warfare Manual Commentary]. A project that this author was involved in. However, a review of these texts some 16 years later, as well as national military manuals, suggests that the dramatic increase in the use of drones, including by non-State actors, means the classification of aircraft and how they are used needs to be updated.
The Air Warfare Manual Commentary states the definition of a military aircraft is “based on Art. 3 and 14 of the HRAW that are generally considered as reflecting customary international law” (para. 2, p. 46). However, it not clear if there is sufficient uniformity in approach by States to confirm such a customary rule exists. The Commentary applies a more definitive approach towards what constitutes a military aircraft than set out above in the United States Air Force manual. Rule 1(x) of the Commentary states:
“Military aircraft” means any aircraft (i) operated by the armed forces of a State; (ii) bearing the military markings of that State; (iii) commanded by a member of the armed forces; and (iv) controlled, manned or preprogrammed by a crew subject to regular armed forces discipline.
A seemingly definitive statement is also reflected in Rule 17(a) which states “[o]nly military aircraft, including UCAVs, are entitled to engage in attacks.” The Manual also appears to authoritatively state in Rule 115(b) that “[i]rrespective of whether or not they are perfidious, in air or missile combat operations” it is prohibited at all times from using “any aircraft other than a military aircraft as a means of attack.”
Notably, this wording is narrower than the Hague Rules which indicates “[n]o aircraft other than a belligerent military aircraft shall engage in hostilities in any form” (art. 16). What is unclear is whether the Air Warfare Manual Commentary provisions are suggesting it is a war crime if aircraft not qualifying as a “military aircraft” are used in an attack. For example, a belligerent who is not subject to “regular armed forces discipline” operating a drone behind enemy lines or in occupied territory.
Looking at State manuals it is difficult to conclude the Air Warfare Manual Commentary reflects settled law even concerning the circumstances in which only military aircraft must be used. The U.S. Air Force manual states “military aircraft may not bear markings of the enemy or markings of neutral aircraft while engaging in combat” (p. 17). However, there is no indication of what “in combat” means.
Further, it is indicated that civil aircraft may carry troops or supplies and there is no requirement that it “be marked as a military aircraft unless used to take a direct part in hostilities” (p. 18). What is missing is reference to the widely held view that civilian aircraft performing combat support or combat service support roles would constitute taking a direct part in hostilities.
The definitive approach in the Air Warfare Manual Commentary can be contrasted with the United States DOD Law of War Manual, which states circumstances may exist where State markings are superfluous. An example being “when no other aircraft except those belonging to a single state are flown” (para. 14.3.3, fn 70).
A lack of uniformity of approach is reflected in other State manuals. The 2004 U.K. Manual on the Law of Armed Conflict states “[o]nly military aircraft may attack military objectives” (para. 12.34). In contrast the 2006 Australian Law of Armed Conflict Manual uses language of entitlement indicating “only military aircraft can exercise the combat rights of a belligerent” (para. 18.14). Examples of exercising those rights includes not only attacking the enemy, but also simply overflying enemy territory.
The 2001 Canadian The Law of Armed Conflict at the Operational and Tactical Levels manual states “[c]ivil aircraft and state aircraft that are not military aircraft (for example, police or customs aircraft) may not engage in hostilities even if their crew and/or their passengers are members of the armed forces” (para. 7.04(3)). Similarly, the 2016 Danish Military Manual on International Law broadly states “[o]nly military aircraft may participate in hostilities” (para. 3.2). What is not clear in either the Canadian or Danish manuals is the scope of “in hostilities”.
The idea that only State military aircraft defined by its markings, type of command and the disciplinary system applied to its crew can exercise belligerent rights is tied to a 1920s interpretation of international humanitarian law. One where the focus of the law was on a lawful belligerent status primarily being available to regular force participants in hostilities.
Prior to the Second World War persons participating directly in hostilities who did not qualify as lawful belligerents were viewed as war criminals. What this means in the 21st Century is that the contemporary definition of military aircraft relies on what is fundamentally 1923 criteria for belligerent status. Problematically humanitarian law rules have evolved considerably since that time.
Unprivileged Belligerency and Air Warfare
As this author has indicated in a recent Articles of War post, I Spy: Espionage, Perfidy and Conflict in the Shadows, the historically narrow State regular armed forces based approach towards lawful belligerency changed significantly in the aftermath of the Second World War. That change was brought on by Allied use of, and support for organized resistance movements in occupied territory, as well as the deployment of specialized intelligence controlled paramilitary and military forces behind enemy lines.
A broadening of lawful belligerency status was first reflected in the recognition in Article 4A(2) of 1949 Third Geneva Convention that members of militias, volunteer corps or resistance movements might qualify for POW status.
Perhaps the most significant change occurred outside of legal texts. That was the recognition of a new status of “unprivileged belligerency”. As Richard Baxter explained in a 1951 article So-Called ‘Unprivileged Belligerency’: Spies, Guerrillas, and Saboteurs (p. 24) belligerents not meeting the criteria for POWs could be equated to spies, and as such they were not to be viewed as war criminals under IHL. Instead, like spies they were subject to prosecution under domestic law of the detaining State, or for security offenses applicable in occupied territory (e.g. Fourth Geneva Convention, art. 68).
Unprivileged belligerency has gained wide recognition since then as can be seen in the U.S. (here) and U.K. (here) law of armed conflict manuals. This new approach towards classifying participation in hostilities highlighted that conduct constituting the war crime of perfidy, which can include feigning civilian status, is significantly narrower in scope than unprivileged belligerency. It is not an international crime to simply be fighting as an unprivileged belligerent regardless of whether that lethality is delivered by means of a drone.
A finding of actionable perfidy depends in establishing intent, as well as applying factors such as remoteness and proximate cause. Given the extensive reliance by States on such irregular warfare during the Second World War and since, adopting the concept of unprivileged belligerency meant that States avoided being responsible for any international crime as a matter of State, superior or command responsibility. That issue only arose if States were directing or condoning perfidy.
The trend towards decriminalizing the participation of resistance organizations and others traditionally considered to be unlawful combatants is also reflected in Article 44(3) of 1977 Additional Protocol I. As has been noted most of the world’s States are Parties to Protocol I and it applies to the Russia/Ukraine conflict as a matter of law.
However, the various manuals setting out the rules governing air warfare have not recognized the impact this broader acceptance of unprivileged belligerency as it relates to the use of aircraft. The Protocol criteria found in Article 44(3) applied to assess the POW status of resistance personnel and indirectly potentially perfidious action does not equate particularly well to the use of drones.
Is the operation of a drone by a “partisan” or special forces operative what is meant by carrying arms openly? Part of the reason may be that traditionally the operation of aircraft by organized resistance movements, or unprivileged belligerents has not been an issue. The proliferation of drones appears to be changing that.
Other associated drone issues remain to be addressed under IHL. For example, determining the lawful status of participants involved in hostilities has traditionally relied on visual signs such as uniforms, emblems or aircraft markings.
For aircraft this became increasingly challenging as the 20th Century progressed due to the adoption of camouflage and because of technological advances that allowed aircraft to operate beyond visual range. Added to this now is the miniaturization of drones.
NATO has classified drones into three categories: Class III (more than 600 kg), Class II (between 150 and 600 kg) and Class I (less than 150 kg). Class I drones can be further divided into Small (less than 150 kg), Mini (less than 15 kg) and Micro (less than 2 kg) (Molloy, Drones in Modern Warfare, p. 15). It is difficult to see how a Micro-drone would be readily classified as a “military aircraft” using the present criteria, although the Air Warfare Manual Commentary contemplated man-portable and even autonomous drones being included in the definition of UAVs (Rule 1(dd), p. 54).
The markings on such a small vehicle are unlikely to be visible to the naked eye unless it is virtually in a person’s possession. Even more challenging is the development of drones designed to look like and mimic birds (e.g. the BioFly project). When the Air Warfare Manual Commentary rules were crafted drones were more readily seen to resemble and act like traditional aircraft rather than miniaturized versions of hobby craft or birds.
The reality is that the operation of aircraft by members of groups not qualifying for combatant status should not be considered as prohibited under international humanitarian law even if the rules in various manuals suggest only State military aircraft may participate in hostilities or carry out an attack. The Air Warfare Manual Commentary does refer to unprivileged belligerency, but in the context of crews wearing uniforms rather than aircraft operated by them while having civilian markings or no markings at all (pp. 245-46).
Interestingly it is suggested in the Commentary that aircraft having no markings cannot engage in attacks (para. 6, p. 252), although the Additional Protocols Commentary states “removing the signs indicating rank, unit, nationality or special function from uniforms” is a lawful ruse (para. 1521, at 443). This is another area where the air warfare rules should be re-assessed given the likelihood that many mass produced or converted drones have no markings, or markings visible to an adversary.
The Air Warfare Manual Commentary indicates that using a drone to kill or wound an adversary while feigning civilian status is perfidious. However, in reaching that conclusion it does not address the more relaxed combatancy status in the Third Geneva Convention and Additional Protocol I, or what the equivalent would be of carrying arms openly. As the Commentary notes “painting civilian markings on a military aircraft has a superficial similarity to a combatant feigning civilian status by wearing civilian clothing” (para. 4, p. 252).
It is not clear why the use of a drone that is technically “non-military” because it commanded by a civilian or controlled by someone not subject to regular armed forces discipline (i.e. an unprivileged belligerent), but is properly marked would be perfidious. Status criteria are not in themselves determinative of treacherous action.
Further, as is discussed in the post referred to above contrary to what is indicated in the Air Warfare Manual Commentary drones feigning civilian status and used mainly for intelligence gathering purposes would not at first glance be acting perfidiously “if they are used in close conjunction with military units in order to identify at target, designate it, monitor the engagement, or assess the results in order to determine whether a re-attack is necessary” (para. 8, p. 252). Extensive state practice in relying on the covert collection of information by civilian agents and disguised military units to facilitate targeting suggests otherwise.
Finally, in terms of classification it is essential that any review of what constitutes a lawful use of drones looks at State practice regarding the use of civilian (non-military) aircraft during hostilities. This would include the U.S. supported air group during the 1961 Bay of Pigs operation, the C.I.A. use of “Air America” planes in Laos (1955-1974), the use of mercenary flown aircraft in various African wars spanning from the Cold War into this century, the use of Blackwater private contractor aircraft to protect convoys in Baghdad following the 2003 invasion, the post 9/11 C.I.A drone counterterrorism program, and alleged Ukrainian “special services” operated drones during the Sudanese civil war.
There is a need to consider what rules govern drone use by State and non-State actors during non-international armed conflict. The Air Warfare Manual Commentary (p. 101) indicates that since there is no combatant status applicable to non-international armed conflict no requirement exists that only military aircraft carry out attacks.
The 2023 Newport Manual on the Law of Naval Warfare states any vessel or aircraft at their disposal to engage the enemy can be used, which includes “the services of private security companies to conduct aerial operations during non-international armed conflict”.
Further, there is “no treaty of customary rule according to which the platforms…must be distinctively marked or recognizable as being used by them for the conduct of hostilities” (para. 12.3.1, at 245). What is not addressed is the steps required for such aircraft not to be considered to have committed the war crime of perfidy based on feigning civilian status. What makes this particularly important is that notwithstanding the renewed emphasis on LSCO it is conflicts not of an international character that remain the dominate form of hostilities.
Aircraft or Missiles?
The second issue that should be re-assessed is how drones are classified. Are all drones aircraft, or are some weapons of war? What about drones that are used more like weapons than platforms that carry weapons? Rule 15(b) of the Air Warfare Manual Commentary refers to hijacked highliners being used as a means of attack, which is reminiscent of the Japanese use of “kamikaze” planes of the Second World War.
However, in a contemporary context the assessment would have to look at the proliferation of what are called “suicide”, “kamikaze” or “shahed” drones. Drones that are used for the strategic targeting of oil fields in Russia, attacks on airfields in Crimea and as tactical level anti-tank weapons. It has recently been suggested that in Ukraine “[t]he vast majority of soldiers dying on the battlefield are now thought to have been killed by drones.”
In practice not all drones carry markings. As Mateusz Piatkowski notes in an Articles of War post, Military Markings And Unmanned Aerial Vehicles, the “practice of non-marking certain types of drone should be further studied in light of a possible emerging interpretation of existing rule as new types of weapons are deployed on the battlefield, such as loitering munitions or kamikaze drones.” In looking at drones as a potential missile the question that needs to be asked is at what point should they be considered to not be military aircraft.
A prime example is “one way attack drones”, which offer “a low-cost way for nonstate actors and proxy forces to strike targets hundreds of miles away with better precision than a rocket or mortar.” Such forces can also include resistance movements supported by States. These are drones that “crash into or explode above their target, and therefore cannot be reused.”
As Bill Boothby has noted “[i]n military doctrinal terms, a weapon which is designed to navigate to a target and then explode on impact on or near that target is a cruise missile.” The fact that “shahed” drones can loiter over a target potentially differentiates them from cruise missiles. However, “there is no difference in the requirements of international law that apply to these types of weapons.” Perhaps even less aircraft-like are FPV drones, which have been analogized to anti-tank rounds, mortar rounds and even sniper weapons.
Perhaps the question that needs to be addressed is whether a drone is primarily a weapons system or a weapon. In this regard the Air Warfare Missile Commentary states (p. 55) “[a] military aircraft armed with missiles and bombs (weapons) is a weapons system that includes, inter alia, the weapons, aircraft, and any systems commanding and controlling the aircraft or providing it data.” Weapons systems carry weapons. “One way” drones do not.
While not a complete answer to the classification challenge it provides a possible way to begin to distinguish between drones as aircraft and those that have primarily an intended use as a weapon.
Without such a distinction Ukraine might soon have millions of aircraft in its air force many of which are not marked according to the historical criteria. A portion of which can be deployed behind enemy lines and occupied territory by groups that many not qualify for lawful belligerent status. Technology, the character of war and international law itself has outpaced dated notions of lawful participation in air warfare.
Conclusion
The proliferation of drones presents significant challenges to historic approaches towards classifying and regulating the use of aircraft during armed conflict. Historical interpretations of international humanitarian law reflect the virtual monopoly that States traditionally enjoyed over the use of aircraft during armed conflict.
However, States support drone use by groups that do not qualify for outdated notions of combatant status (e.g. unprivileged belligerents), and which are using “non-military” aircraft” to kill or wound their adversaries. They are also being employed by non-State groups subject to the law governing armed conflict, which relies on an equal application principle. The groups may not have lawful status but as a means of warfare that does not make their use of drones automatically unlawful.
The technological revolution that spawned drone use by a wide variety of actors has changed warfare. The complacency and overall lack of interest that has been applied to a key, and perhaps the most destructive forms of warfare, air and missile warfare, should be ended. This is an area of law that requires modernization. The rules of 1923 do not provide a realistic basis for regulating 21st Century warfare.
About the Author:
Ken Watkin, BA, LLB, LLM, KC served for 33 years in the Canadian Armed Forces, including four years (2006-2010) as the Judge Advocate General. He was responsible for operational law advice to the Army, Air Force, Navy and Special Operations Forces for a significant portion of the 2001-2010 time period following the attacks of 9/11.
Ken advised the 1993 joint civilian/military Board of Inquiry investigating the Canadian Airborne Battlegroup in Somalia and served as Government legal counsel in respect of inquiries and investigations arising from the 1994 genocide in Rwanda. He was a Foreign Observer to the Israeli Independent Commission investigating the 31 May 2010 Gaza blockade incident, the Charles H. Stockton Professor of International Law at the United States Naval War College (2011-2012), and worked as a counterterrorism/national security consultant with the United Nations and the Canadian government.
Ken is the author of Fighting at the Legal Boundaries: Controlling the Use of Force in Contemporary Conflict (OUP, 2016), awarded the 2017 Francis Lieber Prize by American Society of International Law, is co-author of The Law in War: A Concise Overview (Routledge, 2nd ed. 2023) and has authored nearly 70 articles, commentaries and book reviews on humanitarian and human rights law topics.
The views expressed by guest authors do not necessarily reflect my views, those of the Center on Law, Ethics and National Security, or Duke University. See also here.
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