Guest Post: How International Law Could Work in Transnational Non-International Armed Conflicts: Part I of a Two-Part Series

Guest Post: How International Law Could Work in Transnational Non-International Armed Conflicts: Part I of a Two-Part Series

[Jonathan Horowitz is writing in his personal capacity. He is the Associate Legal Officer at the Open Society Justice Initiative’s National Security and Counterterrorism Program and Naz K. Modirzadeh is a Senior Fellow at the HLS-Brookings Project on Law and Security at Harvard Law School, where she leads the Counterterrorism and Humanitarian Engagement initiative.]


This is the first in a two-part series of postings that attempt to tease out how different international law regimes (specifically the law of armed conflict, the law of self-defense, and international human rights law) interact in transnational non-international armed conflicts (NIACs).  Through conversations between the two of us, and conversations we have had with others, our sense is that looking at public international law generally, as opposed to focusing separately on targetability, other jus in bello constraints, imminence and self-defense, and human rights, illustrates the myriad dilemmas, tensions, and consequences that such a borderless  notion of NIAC would raise.

By way of background, a “transnational NIAC” is the term-of-art for a NIAC where hostilities cross international borders and/or where NIAC targetable individuals cross international borders.  In this type of NIAC, many have argued that the law of armed conflict (LOAC) can follow, like a cloud overhead, targetable individuals to another territory where there are no indications that a NIAC is taking place.  This place could be an empty café in Paris where a targetable individual is making arrangements for a weapons airdrop back where he is fighting; or it could be on a dark street corner in Morocco where a targetable individual is obtaining a zip-drive with the license place numbers and vehicle descriptions of his enemy’s top commanders.  The idea is that the NIAC itself would follow the fighters (thus presumably making their targeting lawful under LOAC), but that the actual decision to target these individuals would hinge on a complex array of other factors borrowed from other areas of law: imminence of the threat posed by the individual, consent from the state where the individual has traveled, or the determination that the state is unable or unwilling to detain or expel the individual.

The purpose of this posting is not to discuss whether “the cloud” of LOAC is or isn’t allowed to follow targetable individuals from places fraught with the violence of a NIAC to a place that is peaceful and calm. Its purpose is to assume that this is allowed and, from there, look at the consequences of this; ask what parts of international law outside of LOAC interact with this type of targetability; and ask whether new mechanisms or doctrines should be put in place to limit those consequences.

It is also important for us to note that what follows does not raise, or answer, all the legal issues at hand. Nor do we even think the legal analysis below is necessarily “correct” in all places. Instead, we hope that this two-part series prompts Opinio Juris readers to voice their own thoughts and comments. Underlying the purpose of this posting is, also, the reality that too often international law, especially with regard to the use of force, develops only after horribly violent events. Wouldn’t it make sense then, to proactively look down the road that we are headed and ask if this path needs correcting?

Due to the complexity of legal issues involved, this posting is divided into two hypothetical scenarios (Part I and Part II) that will be posted sequentially.  Part I involves a transnational NIAC where the “peaceful” State does not permit another State involved in a NIAC to use lethal force on its territory, and where it may indeed extend support to fighters from the non-state armed group. Part II, in contrast, involves a transnational NIAC where the “peaceful” State does permit another State to use lethal force on its territory. In Part II, we will also provide some concluding commentary and pose several questions.

Part I: How International Law Could Work in a Transnational NIAC…without Consent

In 2011, Syrian security forces and rebels (Free Syria Army) engaged in violent fighting that brought the country into what international law defines as a non-international armed conflict (or, NIAC).  At the same time, and largely as a result of Syria’s brutal treatment of civilians during the fighting, Syria fell out of favor with the international community, including the United States.  Since then, the United States has publicly acknowledged that it is providing nonlethal assistance to the FSA. Meanwhile, it has also been reported that the CIA is secretly providing advice to several Arab governments that are supporting the FSA through lethal aid.

Here is where the hypothetical scenario begins: Let’s say that the United States contacts the FSA leadership and tells one of its lead commanders: “We want to assist your political and military planning for the next three months, but we need you to come to the United States to meet face to face. If you make it to Turkey, we’ll charter a secret flight for you to the United States.” The FSA commander asks, “Who will we be meeting?” The American official replies, “our team of Syria experts from the State Department. Also, a military team wants to talk to you about your military needs, but we aren’t prepared to provide direct assistance at this time.” The U.S. official says, “Who could you bring to the meeting?” The FSA commander replies, “myself and two additional top military commanders.”

What the Americans and FSA don’t know is that as the FSA commanders make their way to Turkey to get on the U.S. chartered plane, the plans of the secret U.S.-rebel rendezvous make their way to the Syrian government.  The information enrages President Assad who turns to his top military legal advisor for options. The advisor says, “I’ll be honest with you. There’s a lot we’ve done that’s illegal in this war. But now the law is finally on our side. The rebels, while they are meeting with the Americans, are serving a ‘continuous combatant function’ and, on top of that, would be ‘directly participating in hostilities’ while in the United States because our intelligence confirmed that they will be engaging in military planning.  This means we can attack them. Kill them even. The tricky part will be minimizing civilian casualties to ensure the attack is not disproportionate under the law of armed conflict.”

What could happen next:  After a bit more thinking, the Syrian legal advisor realizes that although the three rebel commanders carry out a continuous combatant function (and are therefore targetable as directly participating in hostilities) that the rebel commanders would not constitute an “imminent threat” while in the United States.  That is, the threat is not, in the language of the Caroline Case, “instant, overwhelming, leaving no choice of means, and no moment for deliberation.” This means that in order for Syria’s attack to respect the rules of sovereignty, Syria would have to either seek U.S. permission to enter its territory to conduct the attack (which it obviously will not do), request that the United States detain and hand over the individuals (which is also obviously will not do), or it would have to carry out the attack in breach of U.S. sovereignty. But if it does the latter, the United States could make a legitimate claim that Syria unlawfully breached U.S. sovereignty; and the United States might respond in kind, possibly after getting Security Counsel authorization – provided that Syria did not pose an imminent threat.

The Syrian legal advisor thinks over the potential consequences of 1) his government being accused of committing an act of aggression, 2) the retaliation it may suffer from the United States, and 3) the prospect of the United States engaging in a war with Syria.  All three outweigh what Syria otherwise considers a key opportunity to attack a non-imminent threat (i.e., FSA commanders in the United States).  The legal advisor then recommends to President Assad that he should refrain from an attack on U.S. soil and instead the Syrian military should target the FSA commanders immediately after their return to Syria.

It could be said that one of the end results of this course of action was that the legal advisor’s choice preserved the regulatory framework of sovereignty and diverted a potential international exchange of force (including a possible international armed conflict). He did this despite the assertion that the law of NIAC allowed Syria to target the three FSA commanders in the United States. The advisor did, however, provide the option for Syria to target the FSA commanders once on Syrian soil, which is clearly permissible under the law of NIAC.

What could also happen next: Unfortunately, President Assad was not pleased with the legal advice he’s been given. He is hell bent on launching an armed attack on the FSA commanders in the United States. His intelligence is accurate and he sees an opportunity to kill rebels before they re-enter Syria; and whatever military strategies they would have devised at the meeting will have been destroyed.  Syria’s legal advisor, struggling to find legal justification to accommodate President Assad, learns that the United States has broadened its interpretation of “imminent threat” such that it does not necessarily require evidence of where an attack will take place, or the precise nature of the attack.  This broad interpretation washes away Syria’s sovereignty concerns since it can now regard the commanders as imminent threats.

Three days later, after the FSA commanders arrive in the United States, Syria attacks (careful to respect LOAC rules of distinction and proportionality), killing all three as well as some of the American officials they are meeting with. In doing so, the attack kills four people in a car and two children and their father as they walked together near the site of the attack. The United States government is outraged. The American public is outraged.  Syria takes to the media to defend its actions: “Yes, Syria violated U.S. sovereignty, but we did so under the United States’ own interpretation of the rules of self-defense in the face of an imminent threat, as well as the U.S. position that a NIAC can follow fighters outside of any geographic scope of armed conflict.  We regret the loss of civilian life, but the attack was proportionate to the military advantage we gained by killing three high-level rebel commanders. For these reasons, the United States has no legal basis to complain. If the United States retaliates with an armed attack she will be breaching Syrian sovereignty and committing an act of aggression. We will have no choice but to attack in kind.”

But the U.S. public is not interested in what precedence the United States set in the past that Syria is now following. The public also does not care what international law dictates or whether Syria has made a fair legal point. Syria killed Americans on American soil, and the U.S. President has no choice but to launch a counter-attack against Syria.  Given the facts, some might argue that to do this legally, the United States needs the U.N. Security Council’s blessing. The U.K. and France are amenable to providing a favorable vote, and both agree that Syria bastardized the concept of imminence and its behavior was outside the scope of international law. China and Russia, on the other hand, have recently taken a liking to the U.S.’s broadened interpretation of imminence—which they want to use to target Chechens and Uighurs living in other countries. As a result, China and Russia object to a UN Security Council resolution that would have authorized the United States to strike back at Syria.

The United States is in a tough position now. Does it attack Syria in what might be a violation of the UN Charter, and in what would likely be regarded throughout most of the world as an obvious act of hypocrisy? Or does the U.S. President try to survive the public condemnation that goes with a nonresponse?

It could be said that one of the end results of this broadened interpretation of “imminence,” along with the application of transnational NIAC targeting rules, is a crippling of one of the most important regulatory tools of international peace and order (e.g., sovereignty) and, additionally, that it allowed for the lawful killings of civilians in countries foreign to where the NIAC is occurring.

In our next posting, we’ll continue this exploration of transitional NIAC legal issues, but will provide a scenario when a foreign State does grant Syria permission to target the three high-level FSA commanders who are part of Syria’s NIAC.

To be continued….

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There is no such thing in customary international law (i.e., no transnational NIAC) and members of the armed forces of any state that are fighting in what otherwise would have been a NIAC should insist that they are fighting in an international armed conflict (e.g., that their entry into the armed conflict has internationalized it), so that they can obtain pow status, combatant status, and combatant immunity for lawful acts of war that are available only with respect to an armed conflict of an international character (e.g., a belligerency or a state-to-state, state-to-nation, state-to-peoples armed conflict).


Also, an “imminent threat” is not even a present threat.  Some who use this phrase might have in mind the old unacceptable Bush Doctrine (i.e., emerging threat) and some might have in mind anticipatory self-defense when an armed attack is imminent (which is contrary to the language of UN art. 51).  Moreover, the debate between the US and UK re: The Caroline had nothing to do with anticipatory self-defense or whether an attack by the rebels, etc. was “imminent.”  Armed attacks by the non-state actors had already been occurring and The Caroline had supplied them and aided and abetted the attacks earlier that day.  Webster was focusing on the actual method or means of response (i.e., “leaving no choice of menas”) and was arguing that the Brits could have waited, apparently until the vessel entered Canadian waters, and should not have attacked at night, etc.  No one disagreed that otherwise the Brits could have attacked non-state actors in the U.S. as a matter of self-defense.  See, e.g.,


Another avenue Assasd could explore that current U.S policy and application have seemed to expand is the evaluation of the “unable or unwilling” factor. It seems that the U.S. has utilized this authority if a State does not give consent for strikes against Taliban figures and associated forces.   In the hypothetical given, the U.S. could be seen as unwilling to stop/prevent/impede the planning of military operations against Syria within its own territory. If fact, the U.S is facilifating such action. This would give Syria another legal basis to violate U.S. sovereignty and attack the FSA. 

Naz Modirzadeh

Eric, I think that’s right. Our assumption is that in the hypo (and probably in reality), given its repeated public statements of support for the rebels, the US could be classified as “unwilling or unable” to arrest, expel or impede the FSA commanders, and that Syria (in the hypo) would be justified, per the US approach to this issue, in determining that the US is “unwilling or unable” to stop the threat. 

Mihai Martoiu Ticu

Luis Posada Carriles is in the US. Cuba could send a drone to blow him up when he attends a wedding party.


A non-international armed conflict exists whenever there is a protracted armed violence between governmental authorities and organized armed groups or between such groups within a State. Transnational NIAC is nonsense


Federico — Thank you for your comment. One of the reasons why Naz and I
wrote this post was because we are seeing an important debate on
conflict typology taking place. Differing views exist amongst various
governments, amongst scholars, and amongst civil society groups. 
Depending on who we speak with, the notion of a transnational NIAC has
been referred to as “completely logical,” “totally ridiculous,” or
somewhere in between. A recognition of a differing of views can also be
found in Prof. Corn’s (South Texas College of Law) contribution to
Intercross at
I’d also have a look at the response by ICRC’s Washington Legal Advisor Daniel
Cahen. With all this in mind, part of what Naz and I tried to do in our
post was to take a step back from the pure questions of what is legally
“right” or “wrong,” and instead look at the issue through the lens of


Federico:  nonsense indeed, and with deleterious consequences for military personnel who fight in another country. Don’t be fooled by the fact that others disagree, there is often disagreement on issues and that does not mean that law has been changed.  As we all know, customary international law is driven by generally shared patterns of opinio juris and it does not change because a minority of states or textwriters prefer something else — especially regarding something that nearly any child could point out to an emperor.


It is equally nonsense to insist that non-state actors in a cross-border conflict (what I would call transnational NIAC) are combatants, given that there is no way that these non-state actors fall under art. 4 GCIII/43 AP1.
Combatants exist only in IAC (conflicts between States, and nothing else).  To hold that a conflict between a state and a non-state actor is not an NIAC for the reason that it crosses a border is to hold that IHL is not applicable at all.  Zegveld described it once sensible: it is not the geographical scope but the identity of the parties to determines the legal character of conflict (cf also Sassoli, HPCR Occasional Paper Series No. 6, SupCt in Hamdan).  Apparently it is possible to still be engaged in a NIAC if one crosses a border, see Statute ICTR’s provision on war crimes.
Jordan, what kind of deliterious consequences do you refer to? Lack of combatant status, which is not supposed to exist anyway in conflicts between states and NSA? How is it ever possible to classify transnational conflicts between state and NSA as international, absent any attribution to the state of the conduct of the NSA?


RJ – nice list of examples, shows indeed some strong legal acceptance for the notion of transnational NIACs , I would also add art 8.2.f of the ICC Statute which treats geographical scope of NIAC even broader than CA3. 


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