Jungle Thunder: A Multinational Approach to Improving U.S. Capabilities in Jungle Warfare

Commentary by Wilder Alejandro Sánchez and Andre Carvalho

Published November 14, 2025

A sizable U.S. Navy fleet continues to sail across Caribbean waters, hunting down vessels suspected of transporting drugs. Meanwhile, U.S. Marines have been deployed to Puerto Rico, where Cold War-era military facilities have been reopened. On November 13, Secretary Pete Hegseth announced via social media Operation Southern Spear, led by Joint Task Force Southern Spear and U.S. Southern Command, which will have the goal of "[removing] narco-terrorists from our Hemisphere." At the time of writing, the general assumption in Washington is that targeted air strikes against Venezuela will occur. More extreme analyses have discussed a U.S. military invasion of Venezuela. The latter possibility is unlikely, given that the number of troops deployed (so far) is not conducive to invading Venezuela like the U.S. operations in Afghanistan in 2001 or Iraq in 2003.

Analyses of a hypothetical U.S. military operation with boots on the ground overlook one critical issue: jungle warfare (JW). U.S. troops in Venezuela would not just fight in Caracas or Maracaibo; they would also have to engage in jungle operations. JW is a unique type of combat, something that the U.S. military has not had to engage in (apart from select operations in Africa) since the Vietnam War. Fortunately for Washington and the U.S. armed services, there are many partners and allies in South America, whose militaries are experts at this type of warfare. In this analysis, the authors propose a method to improve the U.S. military's capabilities and training in JW: the multinational exercise Jungle Thunder.

The Experience of Amazonian Countries in Jungle Warfare and Operations

The Amazon rainforest spans vast territories across multiple South American nations, making it a near-permanent theater of operations whenever armed conflict arises. Several interstate conflicts in South America prominently featured combat operations in jungle environments: the Acre War between Brazil and Bolivia (1902-1903), the Colombia-Peru War (1932-1933), and the recurring border disputes between Ecuador and Peru in 1941, 1981, and 1995. Additionally, the Chaco War between Bolivia and Paraguay (1932-1935)-widely recognized as one of the most significant and bloody conflicts in Latin America during the period-also occurred within a heavily forested, tropical context.

Beyond interstate warfare, internal armed struggles have been a persistent feature of Latin American security dynamics, especially during the Cold War and into the present day. Insurgencies across the region have consistently utilized jungle terrain as a sanctuary and a base of operations. While insurgents often conducted terrorist attacks and engaged in urban combat in densely populated areas, they also relied heavily on remote, forested regions to conduct guerrilla warfare and evade conventional forces. Nowadays, remnants of Cold War-era insurgent groups, particularly those involved in narcotrafficking, continue to operate in jungle environments. In Colombia, these include dissident factions of the Revolutionary Armed Forces of Colombia (FARC), as well as the influential Segunda Marquetalia group, which maintains a presence in remote regions such as the Catatumbo. The National Liberation Army (ELN) remains active as well, often operating in similarly isolated regions. In Peru, residual elements of the Shining Path, particularly those aligned with the Militarized Communist Party of Peru (Militarizado Partido Comunista del Perú), continue to engage in armed activities within the valley of the Apurímac, Ene, and Mantaro Rrivers valleys (commonly referred to by the acronym VRAEM). Likewise, the Paraguayan People's Army (Ejército del Pueblo Paraguayo, or EPP) maintains a presence in remote forested areas of Paraguay.

It is important to note that military operations in the Amazon are not exclusively directed at counterinsurgency or counterterrorism objectives. Armed forces across the region are also tasked with combating illegal mining, narcotrafficking, arms smuggling, illegal logging, and illegal fishing operations. Standard border security operations also require sustained patrolling of isolated Amazonian frontier regions, often accessible only by river or air.

Regional Training in Jungle Warfare

To ensure operational readiness across the Amazon Basin (a region characterized by dense rainforest, challenging terrain, and remote access), South American armed forces maintain continuous training regimens specifically focused on JW. For example, the Peruvian Army operates the Escuela de Selva del Ejército del Perú, a dedicated JW school established to provide its soldiers with the necessary skills to survive, maneuver, and fight in tropical forest environments. In Ecuador, the army operates the Iwia School (Escuela Iwia), an institution with a distinctive mandate, and is specifically designed to recruit and train indigenous soldiers from the Ecuadorian region. Brazil, home to the world's largest share of the Amazon rainforest, maintains an extensive JW doctrine and infrastructure. The Brazilian army's Jungle Warfare Training Center (Centro de Instrução de Guerra na Selva, or CIGS) is globally recognized for its demanding courses. Regional militaries in countries like Bolivia, Brazil, Colombia, Ecuador, and Peru all have units specifically trained in JW.

Even the Venezuelan military maintains several units focused on jungle operations. These include Jungle Infantry Brigades No. 51, 52, and 53. If there is ever a land war between Washington and Caracas, these jungle troops will be critical actors as warfare moves from urban areas to the rest of Venezuelan territory.

The U.S. Military: Jungle Training

Currently, the premier venue for U.S. jungle training is the Jungle Operations Training Course (JOTC), located at the Lightning Academy in Schofield Barracks, Hawaii. The 25th Infantry Division, stationed in Hawaii and aligned with Indo-Pacific Command, plays a unique role in preserving what remains of JW training in the U.S. Army. While the JOTC provides a technically sound and physically demanding environment for JW training, its operational impact is limited by several constraints.

U.S. military field manuals about JW also suggest that this type of knowledge is a lost art. Historically, the US Army doctrine has dedicated limited but focused attention to jungle operations. The most notable example was Field Manual (FM) 90-5: Jungle Operations, first published in 1982. A critical examination of the more recent FM 3-0: Operations manual-the central doctrinal reference for the U.S. Army's operational art-reveals how marginal JW has become within the contemporary multi-domain Operations (MDO) construct. In FM 3-0, jungle terrain is mentioned only in passing. On the other hand, the armies (and other services) in Brazil, Colombia, and Peru have entire manuals dedicated exclusively to JW.

U.S. Military Training in Latin America and the Caribbean

The U.S. military regularly conducts multinational exercises with its Latin American and Caribbean partners. These activities are primarily organized under the auspices of United States Southern Command (SOUTHCOM), the geographic combatant command responsible for most of the Western Hemisphere. Among the key exercises facilitated by SOUTHCOM are UNITAS, TRADEWINDS, RESOLUTE SENTINEL, and PANAMAX-each designed to foster regional cooperation, enhance interoperability, and build partner capacity across a spectrum of security domains.

In recent years, there has been a discernible increase in U.S. military interest in JW, consistent with growing recognition of the operational and strategic challenges posed by dense, tropical environments. A notable example of this renewed emphasis occurred during UNITAS 2021, which Peru hosted. For the first time in the history of this longstanding exercise, a jungle and riverine warfare component was included. Participating forces conducted training in Peru's Amazon region, specifically in the vicinity of Iquitos, providing a rare opportunity for hands-on experience in a complex and austere environment.

Bilateral exercises have also occurred: the Brazilian and U.S. armies have included JW components to bilateral training (such as Exercise CORE 23). Besides Exercise CORE, as of 2025, a total of 47 U.S. officers and sergeants have completed the CIGS course in Brazil. Moreover, in 2025, the U.S. South Dakota National Guard and troops from Suriname carried out a "first-of-its-kind jungle warfare," via which "service members from the SAF [Suriname Armed Forces] and the South Dakota Guard spent 10 days sharing critical skills in survival, navigation, and patrolling." Recently, U.S. troops in Panama carried out JW training with local security agencies.

Recommendation: Exercise Jungle Thunder

While these initiatives represent important steps forward, they remain limited in scope and frequency. Considering the strategic importance of jungle terrain in the Amazon regions, the authors propose the establishment of an annual multinational exercise titled "Jungle Thunder." The primary objective of this initiative would be to provide regular, rigorous training in JW for U.S. Army and Marine Corps units alongside their South American counterparts.

Jungle Thunder could be held annually or biannually, and would ideally rotate among Amazonian host nations, beginning with Brazil, Colombia, and Peru. Other countries within the region, such as Ecuador and Guyana, could also serve as potential hosts, contingent upon their capabilities and willingness to participate. Furthermore, this exercise could be expanded to include U.S. allies with a history of JW training, notably France, the Netherlands, and the United Kingdom, as their militaries also train in their respective greater Caribbean territories and with regional partner nations.

The proposed exercise offers several strategic benefits. First, it would strengthen military-to-military relationships between the United States and its regional partners, fostering deeper operational interoperability and trust. The armed forces of Brazil, Colombia, Ecuador, Guyana, Peru, and Paraguay would likely welcome the opportunity to train alongside U.S. personnel on a more frequent and structured basis.

Second, Jungle Thunder would provide an invaluable opportunity for U.S. Army and Marine Corps units to develop and maintain proficiency in JW, a skill set increasingly relevant to global operations. Furthermore, riverine operations are a capability that the United States military has generally lost since the Vietnam War, the heyday of the U.S. military's Brown Water Navy; hence, U.S. troops would greatly benefit from training in Amazonian rivers. The exercise could also integrate the participation of the U.S. National Guard, particularly units involved in SOUTHCOM's State Partnership Program. For instance, the South Carolina National Guard's partnership with Colombia could be leveraged to support this initiative, thereby enhancing both training outcomes and bilateral defense ties.

Third, the Amazon jungle is ideal for testing emerging defense technologies. The exercise could serve as a proving ground for a wide range of systems, including uncrewed aerial vehicles (UAVs), uncrewed ground vessels, electronic warfare systems, loitering munitions, robotic systems, and advanced camouflage solutions. During her tenure as commander of SOUTHCOM, General Laura Richardson emphasized the potential for the region to function as a testbed for innovative technologies in partnership with the Department of Defense and defense industry stakeholders. Her successor, Admiral Alvin Holsey, continued to support this initiative. Exercises such as Operation Windward Stack, the Hybrid Fleet Campaign Event 2024, and Operation Southern Spear (initiated in January 2025) have incorporated autonomous and uncrewed systems.

Moreover, it is important to acknowledge that South American militaries already employ UAVs for intelligence, surveillance, and reconnaissance missions across the Amazon. These forces can share their operational experience and insights with their U.S. counterparts, thereby fostering mutual learning and enhancing the collective ability to operate effectively in jungle environments.

Conclusions

The U.S. Army, Marine Corps, and other branches of the armed services continue to conduct training in JW. However, this type of training remains sporadic and is typically limited to select units. In contrast, for many South American militaries-particularly those operating within the Amazon Basin-JW constitutes a core component of their operational identity and institutional tradition. Colombia and Peru have conducted sustained counterinsurgency campaigns in the Amazon for decades; as a result, generations of Colombian and Peruvian military personnel have developed deep expertise in counterinsurgency JW. Meanwhile, given its vast Amazonian territory, the Brazilian military considers JW one of its core pillars.

Should the situation between Washington and Caracas deteriorate, the White House could order air strikes against Venezuela. If a land operation occurs, JW will be a critical component of a ground campaign. To be ready, the U.S. military must regain knowledge about this type of combat. And South American militaries can help.

Wilder Alejandro Sánchez is a senior associate (non-resident) with the Americas Program at the Center for Strategic and International Studies in Washington, D.C. Andre Carvalho is a PhD researcher at the Brazilian Army Command and General Staff College and a research fellow at MINERVA. The views and opinions expressed herein are solely those of the author and do not represent the official stance of the Brazilian Army.

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