Updated January 8, 2024
Defense Primer: What Is Irregular Warfare?
Introduction
institutions to provide security, essential services, justice
U.S. military doctrine distinguishes between two types of
and economic opportunity. Stability operations may be an
warfare: traditional warfare and irregular warfare. In
interagency effort.
Department of Defense (DOD) Joint Publication (JP) 1
Joint Warfighting, conventional warfare is characterized as
Foreign Internal Defense. DOD JP 3-22 Foreign Internal
“a violent struggle for domination between nation-states or
Defense characterizes FID as “participation by civilian
coalitions and alliances of nation-states, fought with
agencies and military forces of a government or
conventional forces.” The publication differentiates
international organizations in any of the programs and
between that and irregular warfare (IW), which is defined
activities undertaken by a host nation government to free
as “a form of warfare where states and non-state actors
and protect its society from subversion, lawlessness,
campaign to assure or coerce states or other groups
insurgency, terrorism, and other threats to its security.”
through indirect, non-attributable, or asymmetric activities,
either as the primary approach or in concert with
Counterterrorism. The DOD Dictionary of Military and
conventional warfare.” IW is a joint activity not limited to
Associated Terms defines CT as “activities and operations
special operations forces (SOF); the IW operating
taken to neutralize terrorists and their organizations and
environment includes all domains and the information
networks to render them incapable of using violence to
environment (IE). According to JP 3-04 Information in
instill fear and coerce governments or societies to achieve
Joint Operations, the IE is “the aggregate of social, cultural,
their goals.” They are distinct from counterinsurgency and
linguistic, psychological, technical, and physical factors
stability operations as well as from security cooperation.
that affect how humans and automated systems derive
meaning from, act upon, and are impacted by information,
Counterinsurgency. In JP 3-24, COIN are “comprehensive
including the individuals, “organizations, and systems that
civilian and military efforts designed to simultaneously
collect, process, disseminate, or use information.”
defeat and contain insurgency and address its root causes.”
Previous DOD doctrine characterized IW as “a violent
Operations in Irregular Warfare
struggle among state and non-state actors for legitimacy and
Related activities such as military information support
influence over the relevant population(s).” IW actors may
operations (MISO) or psychological operations, cyberspace
use nontraditional methods such as guerrilla warfare,
operations, countering threat networks, counter-threat
terrorism, sabotage, subversion, criminal activities, and
finance, civil-military operations, and security cooperation
insurgency in their efforts to control the target population.
also shape the information environment and other
In IW, a less powerful adversary seeks to disrupt or negate
population-focused arenas of competition and conflict.
the military capabilities and advantages of a more powerful
military force, which usually serves that nation’s
Military Information Support Operations. Also known
established government. Because of its emphasis on
as psychological operations, MISO are “planned operations
influencing populations, actions to control the IE, to include
to convey selected information and indicators to foreign
actions in cyberspace, play a prominent role in IW.
audiences to influence their emotions, motives, objective
reasoning, and ultimately the behavior of foreign
Missions of Irregular Warfare
governments, organizations, groups, and individuals in a
IW includes, among other activities, the specific missions
manner favorable to the originator’s objectives.” (JP3-13.2)
of unconventional warfare (UW), stabilization, foreign
internal defense (FID), counterterrorism (CT), and
Cyberspace Operations. In JP 3-12, cyberspace operations
counterinsurgency (COIN).
are “the employment of cyberspace capabilities where the
primary purpose is to achieve objectives in or through
Unconventional Warfare. P.L. 114-92, Section 1097,
cyberspace.” They include offensive measures intended to
National Defense Authorization Act (NDAA) for FY2016,
project power in and through cyberspace, and defensive
defines UW as “activities conducted to enable a resistance
measures to protect and preserve the ability to use one’s
movement or insurgency to coerce, disrupt, or overthrow a
own cyberspace capabilities.
government or occupying power by operating through or
with an underground, auxiliary, or guerrilla force in a
Countering Threat Networks. JP 3-25 describes
denied area.” UW is a core component of IW.
countering threat networks as “the aggregation of activities
across the DOD and United States Government departments
Stabilization. Stability operations involve a range of
and agencies that identifies and neutralizes, degrades,
activities from responding to natural disasters to repairing
disrupts, or defeats designated threat networks.”
critical infrastructure and strengthening indigenous
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Defense Primer: What Is Irregular Warfare?
Counter-Threat Finance. JP 3-05 Special Operations
equipment, and training often conducted in hostile, denied,
defines counter threat finance as “activities conducted to
or politically sensitive environments. Many of the IW
deny, disrupt, destroy, or defeat the generation, storage,
component activities listed are coordinated and conducted
movement, and use of assets to fund activities that support
by USSOCOM and SOF. For example, unconventional
an adversary’s ability to negatively affect United States
warfare is led by special operations forces.
interests.”
Conventional forces also play a role in IW. The Irregular
Civil-Military Operations. According to JP 3-57 Civil-
Warfare Annex of the 2018 National Defense Strategy
Military Operations, civil-military operations are “activities
(NDS), released by DOD in 2020, set a goal of maintaining
of a commander performed by designated military forces
an IW core competency throughout the entire Joint Force,
that establish, maintain, influence, or exploit relations
not just the Special Operations Command. Additionally,
between military forces and indigenous populations and
USSOCOM engages with partners, allies, and interagency
institutions by directly supporting the achievement of
components to fulfill its mission. For instance, the U.S.
objectives relating to the reestablishment or maintenance of
Department of State’s Global Engagement Center (GEC)
stability within a region or host nation.”
works with USSOCOM as part of its mission to counter
foreign propaganda and disinformation. Within the federal
Security Cooperation. JP 3-20 Security Cooperation
government, the GEC is the lead for these activities.
counts security cooperation as “DOD interactions with
foreign security establishments to build relationships that
Irregular Warfare in the National Security Strategy
promote specific United States security interests, develop
The IW Annex of the 2018 NDS outlined the principles of
allied and partner military and security capabilities for self-
IW as a core competency of the DOD. The IW Annex notes
defense and multinational operations, and provide United
that China, Russia, and Iran are willing practitioners of
States forces with peacetime and contingency access to
campaigns of disinformation, deception, sabotage, and
allies and partners.”
economic coercion, as well as proxy, guerrilla, and covert
operations, and calls for a revised understanding of IW to
Asymmetric Warfare and IW
account for its role in great power competition. The 2022
While there appears to be no single government definition,
NDS contains some mentions of irregular warfare,
asymmetric warfare is often characterized in national
particularly in the context of competitor’s gray zone
security literature as a type of war between opposing forces
activities, referring to the so-called gray zone between
that have divergent military power, strategy, or tactics. It
peace and wartime.
often involves the use of unconventional weapons and
tactics, such as those associated with guerrilla warfare and
Irregular Warfare in the National Defense
terrorism. Asymmetric warfare is a form of irregular
Authorization Act
warfare. Because of its association with and similarities to
Section 1202 of the National Defense Authorization Act
irregular warfare, the terms are sometimes used
(NDAA) for FY2018 provided that the Secretary of
interchangeably.
Defense may, with the concurrence of the relevant Chief of
Mission, expend up to $10,000,000 during each of fiscal
Irregular Forces
years 2018 through 2020 to provide support to foreign
According to Hague conditions outlined in Article 4(A)(2)
forces, irregular forces, groups, or individuals engaged in
of the 1949 Third Geneva Convention, a country or state’s
supporting or facilitating ongoing and authorized irregular
armed forces or regular forces are those that are (1)
warfare operations by U.S. Special Operations Forces. The
“commanded by a person responsible for his subordinates”;
NDAA for FY2022 amended Section 1202 to extend it
(2) “hav[e] a fixed distinctive sign recognizable at a
through FY2025, while requiring a report on the IW
distance”; (3) “carry arms openly”; and (4) “conduct their
strategy called for in the IW annex of the 2018 NDS. The
operations in accordance with the laws and customs of
NDAA for FY2024 codified the support provision and
war.” Any force that does not meet these four conditions
raised the expenditure to up to $20,000,000 per fiscal year.
can be considered an irregular force. Simply put, irregular
Issues for Congress include whether to limit or expand IW
forces, also known as irregular military, are armed forces
funding, and redefining IW terminology.
that employ irregular tactics. Existing outside of the
conventional military, irregular forces include—but are not
CRS Resources
limited to—partisan and resistance fighters in opposition to
occupying conventional military forces.
CRS Report R45142, Information Warfare: Issues for Congress,
by Catherine A. Theohary.
Special Operations Command
CRS In Focus IF10771, Defense Primer: Operations in the
The United States Special Operations Command
Information Environment, by Catherine A. Theohary.
(USSOCOM) organizes, trains, and equips special
CRS In Focus IF10537, Defense Primer: Cyberspace Operations,
operations forces (SOF) for special operations core
by Catherine A. Theohary.
activities and other such activities as may be specified by
the President and/or the Secretary of Defense. These core
activities reflect the collective capabilities of all joint

special operations forces rather than those of any one
military service or unit. Activities or actions requiring
Catherine A. Theohary, Specialist in National Security
unique modes of employment, tactical techniques,
Policy, Cyber and Information Operations
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Defense Primer: What Is Irregular Warfare?

IF12565


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https://crsreports.congress.gov | IF12565 · VERSION 3 · UPDATED

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