Environment and Consequence: Legal Practice and Risk in Jungle Operations
To our men, British or Indian, the jungle was a strange, fearsome place; moving and fighting in it was a nightmare. We were too ready to classify jungle as “impenetrable” . . . to us it appeared only as an obstacle to movement and to vision; to the Japanese it was a welcome means of concealed manoeuvre and surprise . . . . The Japanese reaped the deserved reward for their foresight and thorough preparation; we paid the penalty for our lack of both.
Field Marshal Viscount William Slim, the Commander of Burma Corps, wrote these words in his 1956 book, Defeat Into Victory: Battling Burma and India, 1942-1945 (p. 139, 143). He described his experience in the spring of 1942 when Japanese jungle tactics dominated British and Chinese coalition troops in Burma, forcing the headquarters of General William Slim entirely out of the British colonial possession. Frustrated, Field Marshal Slim would later handwrite a quick memorandum to his troops to reverse their misfortunes. This memorandum would not only serve as a standard operating procedure for training but also declare a new perspective on jungle warfare that would ultimately help propel them to victory.
The first tenet, he wrote, was that “the jungle is neither impenetrable nor unfriendly” (p. 142). If the Japanese appeared behind the troops, they should “regard not themselves, but the Japanese, as ‘surrounded.’” But his final tenet, “[t]here are no non-combatants in jungle warfare” (p. 143), might give a modern reader, and certainly a modern lawyer, anxiety.
This ultimate point did not derive from any perceived inapplicability of international law. Nor was it an effort by General Slim to unilaterally suspend international law or encourage war crimes. Instead, it was an acknowledgement of the reality they were facing. Their environment dictated how they had to fight and gave cover to an enemy who could seemingly come out of anywhere. Like the soldiers of the U.S. 7th and 5th Cavalry Regiments would also find in Vietnam 22 years later in the Ia Drang Valley (and as LTG Hal Moore would describe decades later in his iconic book, We Were Soldiers Once … And Young), all troops— combat arms, medics, or otherwise—will face immense challenges in jungle warfare (p. 298, 303, 326). Study and preparation for this style of warfare, as General Slim observed after the war, is key to victory.
While conflicts in Ukraine and Gaza rightfully have the world’s attention at this moment, several contemporaneous competitions continue to draw attention to jungle warfare. Tensions between the United States and its potential nation-State adversaries, particularly the People’s Republic of China (PRC), threaten to expand conflict across Southeast Asia and Oceania. Simultaneously, in Central and South America, U.S. allies and partners still grapple with ruthless transnational narcotics and violent extremist organizations (VEOs) who use the region’s dense forests to traffic humans and contraband. Tensions there between States are also on the rise as Venezuela is posturing to invade its U.S.-aligned neighbor Guyana to seize their oil-rich Essequibo territory. Meanwhile, the PRC has poured billions into economic development in Central and South America to increase influence and exploit instability. If current localized conflicts do not escalate to pull more U.S. forces to the region, a larger conflict involving China might.
To be sure, legal professionals across the services are engaged in these areas of rising tension. International law attorneys advise U.S. leaders daily on China’s excessive maritime claims (the infamous Nine-Dash Line), the deployment of certain military equipment on the Korean peninsula, and the interpretations of Japan’s Second World War-era constitution as that nation looks to increase its military posture. In South America and Africa, U.S. judge advocates have accompanied U.S. Special Forces and Security Force Assistance Brigades training partners in border security, drug interdiction, and counter-VEO missions. However, perhaps due to presumptions that legal practice in one region will largely match others, little concerted legal guidance exists for advising in or preparing for jungle environments.
This post discusses various legal challenges that would attend future jungle combat operations. It addresses legal challenges unique to the environment, applicable bilateral and multilateral international agreements, uses of force in non-observable terrain, environmental law dynamics, and recommendations for risk reduction. While it is not comprehensive—it does not, for example, take a legal position on employing anti-personnel landmines or traps—this post aspires to anticipate challenges to assist those eager to better understand and prepare for this type of combat.
The Environment of Battle
Jungle environments cover the equatorial zones of each continent, save Europe and Antarctica. Although non-equatorial forests, such as those in the Franco-German Ardennes or the Ohio Valley, have swallowed armies, equatorial zones present legendarily difficult conditions. It is no coincidence that the first chapter of the U.S. Army and U.S. Marine Corps’ doctrine on jungle operations covers environment, not combat.
While many factors characterize jungle environments, certain characteristics warrant special attention. Jungle environments feature thick vegetation and layered canopies which conceal nearby enemy and friendly forces, civilians, and dangerous terrain features. Jungle conditions are notoriously wet and humid, causing corrosion to equipment, weapons, vehicles, and ultimately, people after just a few days. These conditions also make movement slow as troops must maneuver through restrictive, unpredictable terrain that can grind otherwise-reliable land navigation skills to a halt. If these challenges were not enough, microbial fauna are also rife in jungle environments where malaria, yellow fever, dengue fever, and a host of other diseases proliferate. The environment can also make medical evacuation arduous and resource intensive. These dynamics have afflicted centuries of jungle warfare and persist in conflicts today, such as those in the Philippines and Myanmar.
Arguably, however, the biggest obstacle may be distance. Some equatorial zones can be thousands of miles from the United States over the vast Pacific or across the African continent. This complicates sustainment, even with pre-positioned stocks afloat in the Indian Ocean and the South Pacific. In many cases, the distances put forces outside the “golden hour” reach of critical Role III medical facilities, aggravating the ability to get gravely wounded troops to proper surgical centers. This often-described “tyranny of distance” underscores the need for robust international agreements to secure mutual support with friendly forces, overflight rights, port accesses, and contracts with local vendors. But in jungle environments, as the next section discusses, those agreements may not be easy to access.
Authorities Ad Hoc
The United States never goes to war alone. Similarly, U.S. forces never go to war governed by one set of laws or policies. However, fighting with a long-standing, multilateral coalition such as NATO is different than fighting with one or two partners or an ad hoc alliance composed of partners who may have few overlapping interests. Accordingly, legal practitioners who are familiar with multinational operations aligned with or under a NATO command structure must be ready for a different legal dynamic in jungle environments. Many of the States where jungle operations may occur are not part of any concerted regional or international defense blocs with attending legal regimes.
For instance, in Southeast Asia, despite historical efforts to establish a NATO-like treaty alliance there, none has been successful. The United States must therefore conduct operations in this region under a hodgepodge of bilateral cooperation agreements. The same is true in Central and South America which does not feature any region-specific mutual defense blocs. Most regional or international organizations in these areas, such as the Association of Southeast Asian Nations (ASEAN) or the Organization of American States (OAS), focus on multipolarity through economic, social, and cultural ties, not military.
Furthermore, where a multilateral defense bloc exists, its utility is not guaranteed. For example, the African Union (AU) has a NATO-like mutual defense alliance and an intelligence sharing obligation in its Non-Aggression and Common Defence Pact (arts. 2(c), 4(a)). However, none of the AU Member States are NATO members. The AU is primarily a regional defense pact focused on supporting its Member States, many of whom have histories of colonization by current NATO members, complicating the availability of AU support to U.S. or NATO operations. Additionally, while Article 3(e) of the Constitutive Act of the African Union explicitly encourages international cooperation in furtherance of meeting governance objectives, most AU security activities focus on organizing and mobilizing pan-African peacekeeping forces in response to Africa-based crises. Though the practical military, security, and logistical relationships fostered by the AU Non-Aggression and Common Defence Pact and its implementations would be a significant factor in jungle operations on the African continent, the same may still leave major gaps in legal preparation for any U.S.-led coalition.
Security commitments in these regions therefore are mainly bilateral with limited exceptions, such as the tripartite AUKUS security pact. As a result, U.S. military operations with partners in these regions may struggle to employ shared systems, military regulations, rules of engagement, intelligence agreements, or even official languages that other multilateral defense blocs can provide.
Preparatory Strikes and Unobserved Fires
In addition to treaty-based regime particularities, these operations would also require properly tailored law of armed conflict (LOAC) analyses in an environment that has always created its own style of combat.
Jungle targets often benefit from impregnable canopy coverage and vegetation occlusion over vast tracts of territory. Positive identification in these conditions is enormously challenging. The sporadic effectiveness of airborne or spaceborne intelligence, surveillance, and reconnaissance (ISR) platforms inhibit a critical tool for commanders to conduct modern distinction and proportionality assessments as well as the judge advocates who advise them. It may well be, then, that unobserved preparatory and screening fires into vegetation become required.
Unobserved fires, however, can be extraordinarily risky. To take a short step back, U.S. Army doctrine provides that fires generally come in two varieties: observed and unobserved (paras. 4-85, 86). Observed fires are those that permit an observer to see a point of impact or burst and adjust fire on the basis of what they see (para. 4-85). This is always the preferred method for conducting strikes. On the other hand, unobserved fires are those where a point of impact or burst cannot be seen and cannot be visually adjusted (para. 4-86). This is never preferred when observation is possible.
Observed fires provide the benefit of assuring the commander that a strike is on target, allowing the commander to conserve munitions and focus on the next priority. Observation also provides the commander with a full opportunity to assure that the strike—presumably occurring in pursuit of a legitimate military objective—accords with LOAC’s requirement that it is not directed toward protected persons or places (distinction) and that if collateral damage should occur, the commander has taken all “feasible precautions” to avoid or minimize the same (proportionality) (§§ 5.5.3, 5.11, 5.12.3, 5.12.3.2).
Unobserved fires, by comparison, put these assurances in jeopardy. From a legal perspective, unobserved fires—or even observed fires where the vicinity of impact can be seen but the target, or effects on target, cannot—are one of the riskiest uses of force. Unobserved fires invite skepticism about whether a commander has abided by the principle of distinction. Lack of observation clouds the ability of a commander to discriminate with certainty between lawful and unlawful targets and does nothing to lessen potential liability if something goes wrong. Unobserved fires also complicate a proportionality analysis as to whether a commander has taken all feasible precautions to mitigate or refrain from attacks that would cause harm excessive to the concrete and direct military advantage anticipated to be gained, especially given the current state of technology. Large-scale combat operations do not provide a commander with fiat to ignore international law and commanders remain obliged in all conflicts to take only those lawful and feasible actions that a “reasonable” commander in their position would take, even in the jungle.
From a command perspective, unobserved fires impose additional risks beyond those to civilians. As previously discussed, jungle terrain can obscure both enemy and friendly positions. A commander seeking to employ unobserved fires into thick brush also risks fratricide, even when those forces actively report their positions, a scenario Army jungle operations doctrine strives to avoid (Appendix D). Such fires may also have the undesired effect of identifying friendly positions which might otherwise stay hidden to the enemy. Additionally, unobserved fires may contradict the military principle of economy of force by expending ordnance without having a reliable chance of hitting enemy forces or resources. There is also the ever-present “fog of war,” a constant challenge that even the most sophisticated systems cannot solve to thwart accidents, mistakes, faulty assumptions, or tragic coincidences.
These risks, however, do not mean that a commander must never conduct unobserved fires. Although the law requires commanders to do everything reasonable to avoid collateral damage, the law also does not require soldiers to die or missions to fail simply because a theoretical possibility of collateral damage exists. The result is that feasible precautions involve a subjective analysis. The International Committee of the Red Cross (ICRC) has confirmed this determination in its Commentaries on the 1977 Additional Protocols to the Geneva Conventions, which record that the drafters of Article 57 of Additional Protocol I acknowledged the fact that ultimately, “common sense and good faith” govern the determination of what precautions are feasible.
Accordingly, to connect this component of law to the previously-discussed doctrine, where observation is not possible despite reasonable efforts due to natural environmental obstructions but where military operations are still necessary, unobserved fires may constitute a lawful action for the sake of defending and protecting ground forces or other protected entities vulnerable to enemy attack. Such circumstances may arise, for example, when using surface-to-surface strikes to target an area where reliable intelligence indicates enemy concealment is common but, due to their concealment, positive visual identification is not possible without incurring at least an equally likely chance of harm to the force or the mission. As explored further below too, the use of fires to destroy or thin wooded areas verified by intelligence as likely to be used for enemy concealment could also be lawful under LOAC, as the enemy’s military use of the area would make the area itself consequential to the enemy’s ability to engage friendly forces, making the wooded area a legitimate military objective.
However, the astute commander must not forget that legal mitigation does not mitigate all risks. Such use of fires may not mitigate strategic or political risk. As a recent errant Israeli drone strike on World Central Kitchen workers in Gaza illustrates, the international community is quick to condemn mistakes even when occurring in high-intensity conflicts. Such scrutiny can cause consequences for both international relations and individual officers.
The balance commanders often strive to make is to seat risk management at a level to provide accountability and protect the mission, but not to put forces and the mission itself in danger. In jungle operations, especially when part of a large-scale combat operation with peer adversaries, an uncomfortably low level of delegation may be necessary. This delegation can pair with reporting requirements to mitigate risks, but a delegating command should be sure that delegations do not unduly constrain a subordinate commander’s ability to conduct lawful preparatory or unobserved fires if needed.
Environmental Law in an Environmental War
Another risk that attends jungle operations stems from a relatively modern legal discipline: international environmental law. Social and legal sensitivity to the environmental impacts of war are more acute today than during much of the 20th century. While the British employed them first during the Malayan Emergency, the United States’ use of “Rainbow Herbicides”—most notoriously Agent Orange in Vietnam—heightened concerns about environmental impacts. Those herbicides, a variety of poisonous air-deployed defoliants used for years to eradicate jungle and deny it for enemy use, also exposed U.S., Vietnamese, and foreign individuals to their effects. Use led to decades of lawsuits against both the United States government and chemical manufacturers, resulting in a $180 million settlement in 1984—the largest of its kind at the time—as well as lasting legal and political damage, while rendering no clear tactical advantage.
During the same post-Vietnam timeframe, international law also evolved to emphasize stronger protections for the environment from the effects of war. In 1977, Additional Protocol I to the Geneva Conventions reinforced the Fourth Geneva Convention’s focus on sparing protected places from unnecessary destruction by expressly providing protection for the environment. Article 55 demands that “[c]are shall be taken in warfare to protect the environment” from effects of war which may cause “widespread, long-term and severe damage” and which may threaten the health of local populations. Although the United States is not a party to Additional Protocol I and is silent about whether Article 55 is a part of customary international law, almost all the United States’ allies and almost all States where jungle warfare may occur are such parties.
Additionally, other subsequent treaties and international norms have adopted the “no-harm” approach to environmental impacts of war and reinforced Additional Protocol I’s prohibition on wanton and unnecessary destruction. Most recently, in December 2022, the UN General Assembly adopted Resolution 77/104, titled “Protection of the Environment in Relation to Armed Conflict,” which underscores legal protections from Additional Protocol I for the environment during all forms of armed conflict. Additionally, the Resolution expressed the application of the LOAC principles of distinction, proportionality, and precautions to uses of force that may have environmental impacts.
To be sure, this Resolution does not enjoy the same binding treatment in international law as a Security Council Resolution or a treaty. Additionally, all relevant treaties and statements of customary international law still preserve a belligerent’s ability to direct even highly destructive uses of force against the environment if an enemy is using it for cover, concealment, or camouflage. Nonetheless, it would be reasonable to expect the Resolution to reflect the concerns if not the practice of allies and host nations. For this reason, the Resolution warrants appropriate consideration in U.S. military practice during the planning and execution of jungle operations.
Approaches for Reducing Legal Risk
The first step to reducing legal risk would be the same step to reducing operational risk: planning and training. President Eisenhower’s exhortation that “plans are worthless but planning is everything” echoes in Army Techniques Publication (ATP) 3-90.98, which provides that in jungle operations planning is the first step to preventing fratricide (para. D-6). Leaders must involve legal practitioners in every stage of operational planning to carefully study maps and imagery and identify those areas, features, and conditions which present risk of impact on civilian populations or risk of loss of communication with friendly forces.
Rules of engagement drafting is part of this phase as well and should match the environmental risks. Cross-boundary fires require attention and help formations better avoid fratricide. In an archipelagic environment, cross-island fires may need express elevation of command authority to assure better control of the battlespace, especially where islands may belong to different States. Weapon systems may need additional technical restrictions due to discrimination challenges. Conversely, certain tactics, such as employing canopy-penetrating air bursts from field artillery platforms, may need additional emphasis to highlight their utility. Drafters should also consider the environmental impact that weapons may cause. This is especially true if a weapon system will likely expend toxins into nearby water sources or populated forest areas. While such dynamics may not always override military priorities, proper planning can help identify reasonable precautions and reduce future claims while still preserving the commander’s impetus under LOAC to achieve objectives.
Training is also critical and is not just the responsibility of combat arms troops. Training to conduct thorough analyses into mission, enemy, terrain, troops available, time, civilian, and information considerations (METT-TC(I)), establishing clearly-defined fire control measures, assuring effective primary, alternate, contingency, and emergency (PACE) communication plans, and training on unobserved fires employment in conjunction with partner force or protected persons deconfliction can help commanders and ground troops see limitations in the battlespace and intuit better focus on either pre-staging fire support for certain zones or avoiding other zones all together. U.S. servicemembers, and emphatically military legal practitioners, should also seek to attend the various jungle warfare courses available around the world. Such courses include the Lightning Academy’s Jungle Operations Training Course offered by the 25th Infantry Division and the U.S. Marine Corps’ Jungle Warfare Training Center, as well as courses offered by U.S. partners in places like Brazil, Colombia, Brunei, and India.
Once an operation begins, the second matter, consistent with governing rules of engagement, should be to divert available resources to mitigate risk. Such actions could include vectoring ISR platforms, satellites, non-ISR aircraft, on-ground U.S. troops and forward observers, partner or neutral force troops, or other resources to achieve observation. If observation is not possible, an on-ground commander or fires support coordinator could use sound (para. D-69) to discern impact locations and effects in a zone of fire, or could use other “observer not oriented” techniques (para. 7-7) to help responsibly guide fires to targets.
If neither is feasible, local-level human intelligence of the area would be another recourse. For example, during the Battle of Ia Drang Valley, then-LTC Hal Moore, commander of the U.S. 1st Battalion, 7th Cavalry Regiment, hired U.S.-friendly fighters from local Montagnard villages in the Central Highlands to serve as both interpreters and information sources. When U.S. 105mm howitzers struck forest areas around Landing Zone X-Ray prior to U.S. troops landing, LTC Moore had reliable sources of information to understand local civilian considerations (Moore, p. 45-46, 62-64). Similar information, gleaned from sources with knowledge at the local level, could help effectively mitigate risk.
Technology may also provide enhanced means to achieve effective observation. For example, the Department of Defense continues to work with private industry to develop increasingly nimble small unmanned aircraft systems (sUAS), many of which are capable of guiding themselves through tight spaces. Since the Cold War, the United States has also developed light detection and ranging (LIDAR) capabilities which use high concentrations of laser beam pulses—like how SONAR relies on sound wave pulses—to pierce forest canopies and map terrain and features. Archaeologists have also used the technology in recent years to discover ancient cities in otherwise impenetrable jungles from Cambodia to Bolivia. Because light travels exponentially faster than sound, LIDAR is comparatively much more sensitive to motion and may be useful for identifying and tracking targets in jungle environments. To the extent that the U.S. military is using LIDAR for targeting, however, information on specific applications does not appear to be unclassified or otherwise easily available.
Finally, leaders should take proactive measures to understand and help reduce the unique stress that jungle operations can inflict on troops. For servicemembers on the ground, jungle operations can require significant amounts of time fighting in disorienting and corrosive terrain. For example, as Bryan Perrett details in his book, A History of Jungle Warfare: From the Earliest Days to the Battlefields of Vietnam, the pioneering U.S. jungle-fighters of “Merrill’s Marauders,” organized in 1944 specifically to conduct long-range penetration missions, remained in combat in the Burmese jungle for six uninterrupted months (p. 190). As Captain Fred Lyons, one of the original Marauders, recounted, “[E]very man who marched into Burma so proudly and confidently three months before all either went out as a medical casualty or was left in a Burma jungle grave.” Such conditions can lead to isolation as well as degradation of lethality, discipline, and morale.
Legal practitioners and commanders therefore must prepare their formations for the moral and ethical threat that jungle environments present. They can do so by making sure that pre-mission training and exercises emphasize individual morality, service ethics, legal obligations, and co-dependent accountability at the lowest levels. However, no training can prevent all ills, and certainly training does nothing to prevent the acts of others not subject to the same training. Commanders will therefore also need a swift reporting system, and lawyers will need a faultless communication system with various law enforcement agencies, to address those situations where U.S. troops may be accused of, or become victims of, war crimes or other offenses.
Conclusion: A Good Consequence
In dueling pieces in 2019 and 2020, British military authors David Betz and Hugo Stanford-Tuck and U.S. Military Academy scholar John Spencer debated the severity of another kind of conflict: urban warfare. The former, arguing from years of research as well as experience in urban combat in Iraq and Afghanistan, offered that commanders should view urban environments, like jungle environments, as agenda-neutral with features that commanders can overcome by training and improved technology. Mr. Spencer, on the other hand, argued that the urban environment is anything but neutral due to the people, infrastructures, and technology it contains which form an adaptive “system of systems” influenced by inherent anti-invader agendas.
The purpose of highlighting this debate is not to participate in it. Ultimately whether war is hard in any given place is an unproductive question. In combat, people will do everything they can to make that fight as difficult as possible for their enemy. What is better is to prepare for that hardship by acknowledging the unique dynamics of these domains, dimensions, and environments as much as possible. In this sense, then, the best consequence of this post may not be a better understanding of legal dynamics in modern jungle operations. Instead, it may be a future post, like those above written about urban warfare, which seeks to expand the dialogue and which takes this post to task.
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Nick Allen is a judge advocate and major in the United States Army. He is presently assigned as the Brigade Judge Advocate for the 1st Security Force Assistance Brigade at Fort Moore, Georgia. The views, opinions, and assertions provided in this post, notwithstanding those cited, are the views, opinions, and assertions of the author alone. This post does not necessarily reflect the views or positions of the United States Army, the Department of Defense, or the United States government.
Photo credit: Sgt Rupert Frere