In addition to the international armed conflict between the United States and Israel, on one side, and Iran, on the other, organized armed groups aligned with Iran as part of a self-proclaimed “Axis of Resistance” have opened additional fronts against the United States and Israel. Hezbollah and Houthi forces, for example, have launched a slew of retaliatory attacks across the region from Lebanon and Yemen, respectively. Further widening the conflict, the so-called “Islamic Resistance in Iraq” (IRI), a coalition of Shia militias with close ties to the Islamic Revolutionary Guard Corps, has also intervened on Iran’s behalf, trading tit-for-tat strikes with the United States and Israel (e.g., here, here, here, and here). For the time being, these hostilities are on hold pursuant to a fragile ceasefire, which has seen some instances of apparent violations.

Participation by the IRI in the broader conflict is unique, however, in that some of its constituent elements are part of Iraq’s Popular Mobilization Forces (PMF), which are formally incorporated into the state’s military architecture. Prominent among them are brigades controlled by Kata’ib Hizballah, Asa’ib Ahl al-Haq, Harakat al-Nujaba, and Kata’ib Sayyid al-Shuhada, which have been designated as foreign terrorist organizations by the U.S. government. The PMF rose to prominence in 2014 when Prime Minister Nouri al-Maliki and a leading Shia cleric in Iraq, Ayatollah Ali al-Sistani, called for the organization of new and existing militias to counter the increasing threat posed by the Islamic State (IS). Technically prohibited by Iraq’s constitution, the militias were later assimilated, albeit loosely, into the Iraqi Security Forces by a single-page act of Parliament in 2016 and implementing Diwani orders (for further discussion on the PMF’s integration, see Smith & Singer-Emery).

The recent hostile exchanges between the IRI and the United States and Israel are but the latest episode in an extended series of similar clashes with elements of the IRI following the defeat of ISIS. In 2019, for example, an Israeli drone strike killed a PMF commander near the Syrian border, leading to political calls for the United States to withdraw its forces from Iraq. In December of that year, the United States conducted several airstrikes targeting Kata’ib Hizballah commanders in response to the killing of a U.S. civilian contractor in a rocket attack, prompting a partial storming and weeks-long siege of the U.S. Embassy in Baghdad. In January 2020, the United States killed Kata’ib Hizballah commander Abu Mahdi al-Muhandis alongside Qassem Soleimani, commander of the IRGC’s Quds Force, in an airstrike near Baghdad Airport. And following a drone strike against a U.S. military base in Jordan in 2024, the United States conducted a series of retaliatory strikes against IRGC-affiliated Iraqi militias. This pattern of violent clashes illustrates how the militias continue to enjoy considerable autonomy from the Iraq government’s leadership and demonstrate allegiance to Tehran despite their formal integration into the Iraqi Security Forces.

Nor is there much doubt that Iraq is growing increasingly entangled in the current Iranian conflict(s) through its efforts to defend its sovereignty, including by summoning the U.S. chargé d’affaires and Iranian ambassador to account for various military actions on Iraqi soil, while simultaneously attempting to rein in the PMF’s conduct.

Noteworthy, however, is the Ministerial Council for National Security’s vague authorization in March purporting to allow the PMF to exercise self-defense against U.S.-Israeli attacks. Elaborating on the move, Prime Minister Mohammed Shia al-Sudani, who chairs the Council, explained that

In light of the unjustified attacks and grave violations of Iraqi sovereignty, including the targeting of official security headquarters, the Council decided the following: To confront and respond to military attacks carried out by military aircraft and drones targeting the headquarters and formations of the Popular Mobilization Forces Commission and other formations of our armed forces, using available means, in accordance with the right to respond and self-defense.

According to an Iraqi defense official, the “authorization means Iraqi military units, including the PMF, will not need permission from central command to respond to any attack. The decision was necessary, and Iraq must protect itself,” adding that “the decision to respond will be left to the discretion of the units, and they must respond to any attack they face.” Although Iraq has condemned strikes by all sides, Prime Minister Sudani continues to refer to the PMF as a “fundamental component of [Iraq’s] national security system.”

The PMF’s status as a de jure state organ of Iraq and the Council’s authorization raise the question of whether the ongoing U.S. armed conflict is best characterized as non-international (with the IRI) or international (with Iraq). Aside from any U.S. domestic legal or political implications, the distinction is significant in the international legal contexts of the targeting of persons and in detention, for lawful combatants and prisoner-of-war status only exist in international armed conflicts. An international armed conflict also has other implications such as world-wide application of the grave breaches provisions of the Geneva Conventions. Those distinctions may be of minimal practical significance now while a ceasefire remains at least largely in place. And legal matters pertaining to detainees will not arise as long as any hostilities are generally confined to the air and naval domains. But these legal distinctions would all loom large in the event U.S. ground forces are ever introduced into Iraq following a resumption of hostilities. Especially so considering the ongoing debate regarding whether incorporated members of armed forces—like those who belong to the PMF in Iraq—must observe the conditions set forth in Geneva Convention III to qualify as prisoners of war (art. 4A(2)). While a similar inquiry bears on the jus ad bellum analysis (e.g., the resort to force under the UN Charter) of the conflict within Iraq, that subject is beyond the focus of this essay.

Conflict Classification and Ultra Vires Acts

The widely accepted conditions for international armed conflicts are set forth in Common Article 2 to the 1949 Geneva Conventions. Among other bases, an international armed conflict exists in the event of an “armed conflict which may arise between two or more of the High Contracting parties, even if the state of war is not recognized by one of them.” While the Conventions do not further refine the criteria for an “armed conflict,” there is broad agreement that the intensity threshold for international armed conflicts is quite low; any resort to armed force between two States suffices (Tadić, para. 70; ICRC’s 2025 Commentary to GC IV, art. 2, paras. 288–89).

The relevant issue here is not the conflict’s intensity, but whether it is between two States. One might argue that the PMF’s conduct is ostensibly imputable to Iraq as one of its de jure state organs. This might be the case pursuant to the rules for attributing conduct to a State under the law of State responsibility, a detailed discussion of which is beyond the scope of this essay. Suffice it to say that by that body of law, it is widely accepted that “[t]he conduct of an organ of a State or of a person or entity empowered to exercise elements of the governmental authority shall be considered an act of the State under international law if the organ, person or entity acts in that capacity, even if it exceeds its authority or contravenes instructions” (ILC’s Articles of State Responsibility, art. 7). So long as an organ acts in an official – rather than personal – capacity, their conduct is attributable to the State.

The law of armed conflict’s ascriptive rules operate differently, however. While the conduct of de jure organs is presumably imputable to the State in most cases under that body of law, its substantive rules carve out narrow exceptions for purposes of conflict classification. As the ICRC’s 2025 Commentary to Geneva Convention IV explains,

It is important, however, to rule out the possibility of including in the scope of application of international humanitarian law situations that are the result of a mistake or of individual ultra vires acts, which – even if they might entail the international responsibility of the State to which the individual who committed the acts belongs – are not endorsed by the State concerned. Such acts would not amount to armed conflict. The existence of an international armed conflict is determined by the occurrence of hostilities against the population, armed forces or territory of another State, carried out by State agents acting in an official capacity and under instructions or by other persons specifically instructed to carry out such hostilities by State agents or organs, and not done in error. When a situation objectively shows, for example, that a State is effectively involved in military operations or any other hostile actions against another State, neutralizing enemy military personnel or assets, hampering its military operations or using/controlling its territory, it is an armed conflict. The existence of an armed conflict must be deduced from the facts (art. 2, para. 311).

Multiple military manuals provide similar understandings of acts by apparent state organs that nonetheless fail to trigger an international armed conflict (see U.K., para. 3.3.1; Norway, para. 1.33). According to France’s 2022 Manual of the Law of Military Operations, for instance,

The definition of [international armed conflict] is rather broad because, contrary to [non-international armed conflict], there is no specific threshold of duration or intensity of the confrontation; however, there must be a “belligerent intent” Consequently, [international armed conflict] does not include unintentional causation of harm, such as merely erroneous or accidental cross-border firings, or acts by a State agent who oversteps their instructions (ultra vires acts) without the later endorsement or acquiescence of the State to which they belong (para. 1.1.1).

While recognizing that a State can act only through its agents, the critical inquiry is therefore whether the State in question objectively intends to engage in an armed conflict. Rogue actions by military forces undertaken without the State’s imprimatur, even if they fall within the purported scope of those forces’ official duties, fall short of triggering an international armed conflict.

Classifying the Current Conflict  

There is little dispute that, prior to the Ministerial Council for National Security’s decision and Prime Minister al-Sudani’s statement in March, the IRI has not been acting on the instructions of the Iraqi government in its violent exchanges with the United States and Israel. As such, observers have long viewed the recurring conflict between the parties to be non-international in character. This appears to be the assessment, for example, of the Geneva Academy’s “War WATCH” project.  Though the extent to which its authors have taken recent events into consideration is uncertain, they emphasize that, “[a]lthough formally part of the Iraqi armed forces, like many other factions within the PMU, [the IRI] operate independently from the Iraqi State. Various sources affirm that each of the IRI factions relies on its own chain of command.” Despite periodic claims to the contrary, the IRI’s status as a de jure Iraqi organ does not alter the fact that its unsanctioned conduct prior to the outbreak of the Iran conflict in February is not imputable to Iraq for purposes of internationalizing the armed conflict with the United States and Israel (for a jus ad bellum analysis of prior attacks on the PMF under an “unable or unwilling” approach, see Schmitt).

[Note, the War WATCH project separately maintains that U.S. attacks on IRI forces located within Iraqi territory without Iraq’s consent have initiated a distinct armed conflict that is international in character. It is a conclusion with which I disagree, in no small part due to the absence of belligerent intent.]

The Council’s ambiguous decision in March authorizing the PMF to exercise self-defense complicates the analysis. An argument that the once-non-international conflict has now been internationalized is relatively straightforward. It would not be unreasonable to conclude that the Council’s action means that hostilities by the IRI subsequent thereto have fallen within the State’s instructions and are therefore not ultra vires. Going one step further, one might also conclude that it serves as a post-hoc ratification of the IRI’s conduct immediately preceding the announcement.

Yet, if belligerent intent to resort to force is a central question for classification purposes, the Council’s token authorization strikes me as hollow in that regard. Based on the totality of the circumstances, I still struggle to find that the United States and Israel are engaged in an armed conflict with Iraq. Considering the IRI and PMF’s track record of acting independently and its allegiance to Iran and the IRGC, coupled with repeated U.S. calls for Iraq to accept responsibility for the former’s conduct, the announcement may be better understood as an attempt by Iraq’s leaders to consolidate domestic political control under the guise of defending Iraqi sovereignty. It is a close call.

Ongoing framing of the issue by Iraqi officials supports a conclusion that it is component armed groups, not the Iraqi state itself, which are in fact in armed conflict with the United States and Israel. In response to a question from a Kurdish official on whether the Council’s decision means “the Iraqi government will now fight the Americans,” for instance, an Iraqi spokesperson was unequivocal: “Absolutely not. It is against elements that target them.” That Iraq’s other security forces have gone to great lengths to restrain the PMF’s attacks is also inconsistent with belligerent intent. Indeed, in early March, Iraqi leaders emphasized that “major efforts are underway to prevent any attacks from being launched from Iraqi territory,” including by threatening offenders with prosecution and preventing Kata’ib Hizballah from (again) attacking the U.S. embassy.

Accordingly, while the argument is not unassailable, I believe the conflict remains better characterized as non-international for now, though Iraq may be inching toward internationalizing it in the future.

Conclusion

The best view is that formal incorporation of the PMF into the Iraqi Security Forces and the March authorization to exercise self-defense have yet to transform the non-international armed conflict between the IRI and the United States and Israel into an international armed conflict. The determinative question remains one of intent. On the available evidence, it is challenging to conclude that it is Iraq, rather than the IRI, that is party to the conflict. The better view is that Iraq is continuing its struggle to assert control in the aftermath of its reconstruction and conflict with IS. Even if not party to an international armed conflict, it is important to recall that Iraq would still owe international legal obligations pertaining to the PMF’s conduct, including the duties of due diligence and to ensure respect for the law of armed conflict. And, as stated, Iraq may also still be responsible for the PMF’s conduct nonetheless under the law of State responsibility, though there is a strong argument that actions on behalf of a different State do not fall within the PMF’s official capacity. This is a developing situation, with a need to watch this space.

FEATURED IMAGE: People wave Iranian flags from the bed of a truck displaying a banner depicting Grand Ayatollah Ali Sistani (L), Iraq’s highest Shiite Muslim authority, and Iran’s slain supreme leader Ayatollah Ali Khamenei during celebrations welcoming the two-week ceasefire between the United States and Iran in Baghdad’s central Tahrir Square on April 8, 2026. Iraqi armed factions loyal to Iran and operating under the banner of the “Islamic Resistance in Iraq” announced a two-week halt to attacks they had launched since the start of the war in the Middle East against “enemy bases” in Iraq and the region. The announcement came shortly after Washington and Tehran declared a ceasefire for the same period. (Photo by Ahmad Al-Rubaye / AFP via Getty Images)