Why did the Popular Front for the Liberation of Palestine outperform Fatah in their joint conflict with the US-allied monarchy during the Black September conflict in Jordan? What makes the Abu Sayyaf Group and the New People’s Army in the Philippines more or less effective than one another as they both fight against the government of a key American ally? In past and present conflicts, armed groups involved in conflict with governments have demonstrated their ability to pose serious challenges to such states in ways that may demand attention from the United States and its allies and partners, even with the shift toward prioritizing strategic competition in the Indo-Pacific. From the Philippines to Ethiopia to Yemen, these actors are challenging state sovereignty across the globe. In many cases, armed groups put at risk the stability of partners, countries, and regions that are vital to American and more broadly Western interests in strategic competition. They threaten to undermine key US partner governments, they jeopardize US access into critical regions, and they pose a challenge to broader international security issues like freedom of navigation on the seas and the free flow of commerce and energy supplies. To address this reality, policymakers need to be able to understand which of these armed groups present the greatest military challenge, especially amid the declining share of policy attention, time, and resources that can be devoted to the problem on an increasingly cluttered landscape of strategic challenges.

With fewer means available to confront these actors, how can policymakers do triage and assess which ones pose the greatest threats to such US and Western interests? My research shows that a promising way to do so is through the use of task-based indicators of combat effectiveness (e.g., ability to conduct ambushes, use of cover/concealment and dispersion). Groups that score well on them are more effective in combat and consequently pose a higher level of threat. Moreover, I show that armed groups’ recruitment practices—how they select, train, and induct members—shape their combat effectiveness, and consequently, the level of threat that they pose.

Yes, Armed Groups Still Matter

Armed groups and the civil wars in which they fight continue to pose a significant threat to the interests of the United States and its allies and partners, particularly concerning the relationships, the access that they facilitate, and broader international security priorities that the United States and other Western powers have. For starters, civil war remains the prominent form of global conflict, with one dataset published in 2019 noting a “sharp rise” in civil wars over the past decade. Going to the individual conflict and country levels today illustrates the nature of this threat more clearly. For the past several years, the Houthis in Yemen have consistently targeted key economic and civilian infrastructure in Saudi Arabia (which remains a primary American partner in the Middle East), in addition to their significant territorial gains in Yemen since 2014. In 2021, the Houthis conducted 325 such cross-border attacks against Saudi Arabia using unmanned aerial vehicles and ballistic missiles, and 45 such attacks in 2022 prior to the (now-expired) ceasefire. The group also expanded its targeting to another key US regional partner, the United Arab Emirates, via engagements that included an attack on al-Dhafra Air Base, which houses American troops. The Houthis have also repeatedly demonstrated their capability to attack maritime shipping in the Red Sea and Bab al-Mandeb, a key global chokepoint. In Iraq, Iran continues to support armed groups like Kata’ib Hezbollah and Asa’ib Ahl al-Haqq, which have continuously threatened and conducted attacks on American bases and troops, fomented chaos in Iraq’s fragile political system, and deliberately targeted oil fields in Iraq as recently as June. It remains an open question exactly how much control Iran actually has over these actors, leaving the possibility of even more escalatory attacks in the future.

Parts of Sub-Saharan Africa—recently reaffirmed as “critical” for American “global priorities”—are not different. Al-Shabaab continues to present a significant threat to not only the Somali government but the wider Horn of Africa. This threat is clearly concerning to the United States, given President Joe Biden’s decision this past summer to send more American forces back into Somalia, provide “standing authority” to target al-Shabaab’s leadership, and carry out airstrikes as recently as this past Sunday. In Ethiopia, the Tigrayan People’s Liberation Front continues to wage an insurgency against the central government that started in late 2020 and has destabilized the Horn’s most strategic state and a longstanding US partner. Boko Haram—or, more accurately, the two main factions of the original group—remains active in northern Nigeria and has demonstrated past intent and capability to disrupt oil exploration in the country. The capabilities of Islamist insurgents in Mozambique have necessitated intervention from Rwanda and even the United States on the part of the Mozambican government, and recent developments in the country threaten a key source of liquified natural gas. In Southeast Asia, the Philippines—a strategic location for deployments and rotations of US forces as well as for potential US operations in a conflict against China—required the help of American special operations forces back in 2017 to combat its own ISIS-related threat, and continues to face internal threats from several other armed groups. Strategic competitors may leverage armed groups as part of their own strategies, as Russia demonstrated in Ukraine and elsewhere over the past decade. In the same vein, recent research on Beijing’s military strategy indicates that in a conventional conflict, China may resort to irregular warfare–style activities that very much overlap with armed groups’ ways of combat.

So, What to Do? Learning from the Past to Inform the Present

In an article published in Security Studies, I show how we can determine, prior to a conflict’s conclusion, which armed groups pose the biggest threats by evaluating combat effectiveness using seven task-based indicators. This approach differs from other commonly used measures like territorial control or number of fighters. This type of combat effectiveness is more likely to be achieved by groups whose recruitment practices—that is, how they select, train, and induct members—are consistent and comprehensive. In the article, I demonstrate this via a comparative analysis of the three main insurgent groups that participated in the Black September conflict in Jordan (1968–1971), a civil war in which ten Palestinian fedayeen armed groups tried to overthrow the monarchy in Jordan. The analysis is based on thirteen months of fieldwork in Jordan, Lebanon, and the United States that included: (1) 105 interviews I personally conducted in Arabic with ex-insurgent commanders and fighters, retired Jordanian military and intelligence officials, and former United States government diplomats and intelligence officials who served in Jordan during the conflict; and (2) English and Arabic archival documents gathered from public and private or restricted collections across the three countries.

My analysis leverages these various sources to show how the Popular Front for the Liberation of Palestine (PFLP) outperformed Fatah and the Democratic Front for the Liberation of Palestine (DFLP) during the most intense period of fighting in the civil war as a result of the groups’ differences in recruitment practices (what I call robust versus deficient). The PFLP’s robust recruitment practices included consistently applied membership criteria, a background investigation, and full-fledged military training and indoctrination. This contrasted with the deficient practices of Fatah and the DFLP, which both allowed anyone to join, provided inconsistent or inchoate military training, and varied or no indoctrination. As a result of the PFLP’s recruitment practices, the group was able to successfully execute ambushes, use cover and concealment, and perform affirmatively on the other task-based indicators during the conflict, while Fatah and the DFLP both demonstrated the opposite.

Triaging the Contemporary Armed Group Threat

My historical findings from the Black September conflict in Jordan, developed more fully in an underlying book project, have implications for contemporary operational assessments of armed groups that can in turn inform the policy challenge discussed earlier. In particular, the findings enable assessments of the threats posed by armed groups both in real time prior to a conflict’s conclusion and even before the major fighting begins. The same seven indicators used in my historical analysis can be applied to contemporary armed groups using information on their combat operations drawn from media reports, social media, research that leverages fieldwork in the relevant conflict zone, and open-source datasets. These assessments can then inform policymakers as to which armed groups actually present an acute threat and should therefore be given a priority claim to the limited resources in order to respond.

To briefly illustrate this, consider the earlier example of the Philippines (especially given its postulated central role for US operations in a future conflict against China). There are several armed groups actively fighting the central government, such as the Abu Sayyaf Group (ASG), the New People’s Army (NPA), and remaining elements of the Moro Islamic Liberation Front (MILF) and Islamic State–Philippines. Analysts assessing the capabilities of these various armed groups should examine their abilities to execute the seven tasks I outlined as measures of combat effectiveness. For instance, reports indicate that the ASG has demonstrated the ability to conduct ambushes on multiple occasions as recently as September 2021. Likewise, the NPA has demonstrated the ability to conduct ambushes throughout its history up to the present. Substantiating this task execution via other information sources according to the coding guidelines I outlined and doing the same for the other six indicators of combat effectiveness can provide a general assessment of these armed groups’ performance and the corresponding threats they pose. Affirmative scores on all seven tasks would indicate a combat effective group to which the maximum available attention and resources should be devoted to address the corresponding threat.

Examination of these armed groups’ recruitment practices can be informative to both understand why these armed groups are effective (and others ineffective) and also provide a sense of potential threat prior to the onset of major fighting. For instance, like the PFLP did in Jordan, the NPA devotes considerable time to carefully screening and selecting combatants and then leveraging the group’s ideology for indoctrination and training, per field research published in 2018. A detailed examination of how the NPA and other armed groups in the Philippines recruit their combatants using the same varied mix of information sources can help shed light on: (1) why such armed groups may or may not be combat effective at present; and (2) the potential for changes in their combat effectiveness (and, by extension, the threats they pose) depending on the trajectory of their recruitment practices. Moreover, in situations where armed groups are forming but combat has not yet started (thereby limiting the applicability of the task-based indicators), a focus on recruitment practices can point analysts to which groups might ultimately be the most effective in combat and will therefore eventually present the greatest threat.

As the United States and its allies and partners continue the shift toward a primary policy focus on China and strategic competition, they are trying to leave behind the past twenty-plus years of operations aimed at countering armed groups. Yet, as I (and several others) have demonstrated in these pages, such actors still present significant challenges on a global scale and, more importantly, actively threaten the stability of key countries and regions that are critical for US interests in strategic competition and possible conflict. Moreover, strategic competitors themselves have resorted or may resort to leveraging these actors for strategic gains. This reality requires policymakers to be able to assess which armed groups present the greatest threat in order to efficiently apply what limited attention, time, and resources they have to mitigating the challenge posed by these actors. Policymakers can use task-based indicators of combat effectiveness to assess which armed groups present the greatest threat in an ongoing conflict. They can also use the understanding of recruitment practices as a source of combat effectiveness to assess which armed groups might be effective in circumstances where data relevant to the task-based indicators does not yet exist (like at the start of a conflict before major fighting has occurred). In this way, the United States and its like-minded allies and partners can continue the priority shift in focus toward strategic competition with China while ensuring the greatest threats from armed groups are not left unattended.

Dr. Sam Plapinger is a research scientist at CNA, a nonprofit, nonpartisan research and analysis organization in Arlington, Virginia. He spent the past two years as the embedded CNA field representative to the commander of US Naval Forces Central Command/Fifth Fleet in Bahrain, conducting on-site research and analysis for the senior US Navy commander in the Middle East. At CNA, his work has focused on strategic competition, irregular warfare, urban warfare, force design, and fleet operational issues. His book manuscript, Combat Effectiveness in Civil War: How Insurgent Groups Generate Fighting Power, explains why some insurgent groups are more effective in combat than others.

The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, Department of Defense, or that of any organization the author is affiliated with, including CNA.

Image credit: Ilyas A. Abukar, AMISOM Public Information