The legality of exercising self-defence against the non-state actors is one
of the disputed concerns of the jus contra bellum. In the practice of states,
the right to self-defense against non-state actors is increasingly invoked and
accepted. Nevertheless, the recognition of this right must resolve a fundamental
obstacle: that of explaining why the host state's rights, particularly its right
to territorial sovereignty, are not infringed by the self-defensive force used
within its territory.
When it comes to the states exercising self-defense against non-state actors,
they rely on the host state's involvement with those actors to justify the use
of force in the territory of that state. In this article, the significance of
the principle of necessity has also been illustrated that has to be considered
while exercising the right of self-defence against the non-state actors.
Moreover, the major problems that come up when the victim state exercises the
right of self-defence against the non-state actors, have also been looked at.
The right of self-defence mentioned under article 51 of the United Nations
Charter (UNC) acts as an exception to article 2(4) of the United Nations Charter
which prohibits the use of force. The major concern that arises is that the bare
text of article 51 talks about the right of self-defence against the acts of a
state or against the state actors and this can be misused as a particular state
can attack another through the help of a non-state actor, further encouraging
terrorism. So, this article tries to analyze the existence this right of self-defence
against such terrorist groups i.e. the non-state actors.
Military and technological advancements and their availability to the private
actors, has increased the destruction capacity of the non-state actors. This
makes it the need of the hour to provide some attention to the concept of the
non-state actors. Regrettably, the term only provides a negative definition,
dissociating itself from the legally settled term the state. The realization
about how destructive the actions of these groups can be, has made it essential
to emphasize on the right of self-defence against them and to provide the
states with the same right to defend the territorial integrity, sovereignty and
political independence of their own state.
The point of self-defence becomes more severe when a particular state has been a
victim of the threat possessed by these irregular armed groups, and the Security
Council fails to take any action or to give power to these states to take any
action. The non-state actors by acting under the control of some states that
give shelter to terrorism, impose threat on other states and carry out armed
attacks in other states and thus breaching the sovereignty of the fellow states.
There exist certain circumstances where it might be valid to not provide a
particular state with the right of self-defence as the other state must have
already acted in self-defence and this is to be noted that there definitely
cannot be a right of self-defence against the right of self-defence.
The majority of the issues that come up while exercising self-defence against
non-State actors, are centered around Article 51 of the United Nation Charter,
either to demonstrate that the restrictive inter-State understanding is not
supported by the language of the provision or intended by the drafters, or to
identify a different standard of attribution of the non-State actors' attack to
the host State. The general notion says that article 51 may not restrict the
right of self-defence against the non-state actors, but it eventually fails to
draw a link between the host state and the victim state.
Sovereignty has been recognized by article 2(1) of the UNC and is a crucial
aspect which must not be ignored or breached by the actions of any other
state. There are instances when this sovereignty is harmed by the acts of an
irregular armed group. According to the International Commission on Intervention
and State Sovereignty, sovereignty in the Westphalian sense of the word has come
to mean the legal identity of a state in international law. The right to
self-defence hence turns out to be the most crucial weapon in order to defend
the sovereignty of a particular state, which is to be addressed in this paper.
Which State's Territory May Be Used For Self-Defence Against Non-State Actors?
The initial idea of using justified force against the non-state actors is that
this measure may be taken in the state where the latter might be found, i.e. the
action must be taken in the territory of the state that is harboring the
irregular armed groups. In support of this claim, there exist the United Nation
Security Council Resolution 1373 that states "harbouring of terrorists as an
action which constitutes a violation of international law".
There are certain states that do not agree with this particular way and do not
even identify the presence of these non-state actors or irregular armed groups.
In order to deal with this situation, there exist the 'unwilling and unable'
doctrine that eventually justifies the action of self-defence of one state on
the territory of another state when the latter does not want or is unable to
control or eliminate the risk evolving from the wrongful activities occurring on
its territory. Moreover, even in Lotus case, the Permanent Court of
International Justice i.e. PCIJ held that every state is obligated to use due
diligence so that it can prevent criminal activities originating from its
territory against other states.
This was further confirmed by the ICJ in the Corfu Channel case that every state
has the obligation of not knowingly allowing its territory to be used in a way
that endangers the rights of other states.
The next issue that comes into the picture with respect to this is that certain
terrorist groups are not associated with any particular state, i.e. these
organizations are planned in one state, financed from another state, plan the
attack in a third state and the attack takes place in the fourth state. The most
prominent examples for the same are Al-Qaida that can be traced from Pakistan to
Nigeria and Islamic State that can be found from Afghanistan to Mali. Another
example of such an attack is the 9/11 where, as per the findings of the
US-American secret services, the financing of the attack could be traced from
Saudi Arabia whereas the cell that implemented this attack, was composed of Arab
students that lived in Germany. If any particular stage of people is removed,
then this crime would have been impossible, and it turns out that all the people
involved were equally responsible and had their part to play. However, the
government of Afghanistan claimed that there was no involvement of the
government in this particular attack.
Talking about a way forward to this particular issue, the first thing that has
to be kept in mind is the unjustified breach of the sovereignty of any state,
i.e. the attack while exercising the right of self-defence must not be exercised
in any state which was not aware of this activity and which didn't act as a
shelter for the unlawful activities of the non-state actors. However, the right
of self-defence can be eventually exercised against the non-state actors in the
states where they are present in that particular moment, and the latter must
also co-operate and help in locating these irregular armed groups. In simple
words, the victim state must be justified in taking action against the non-state
actors in order to eliminate future possibilities of such attacks.
Article 51 And The Concerns Of The Present World
Article 51 provides a state with the right of self-defence when there occurs an
armed attack against it. In most cases, this armed attack is carried out by
a state. However, there exist certain unrecognized entities as well, so-called
de facto regimes, may cause an armed attack. Article 51 lays down three
conditions for a state to use force against some other state. Firstly, for
exercising this right, the state must be under an armed attack. Secondly, the
state must also report to the Security Council about the actions undertaken by
it in order to defend itself and lastly, the state shall only use force after
the Security Council has taken all such measures necessary to maintain
international peace and security.
Initially, the use of force while exercising the right of self-defence was
justified only against a particular group and not against the non-state actors
or irregular armed groups. Earlier, even the ICJ followed this state-centric
approach as it denied Israel's claim to use of force under the right of self-defence
against the terror attacks that originated from the Occupied territories in the
case of Advisory Opinion on the Legal Consequences of the Construction of a Wall
in the Occupied Palestinian Territory. The court eventually held that there were
two reasons why Israel could not invoke the right of self-defence.
The first was because Israel didn't claim anywhere that there was any state
behind these attacks, i.e. the claim did not mention any particular state that
was attributable to this terror action.
The second was since the actions originated from a territory that was under the
control of Israel, the Security Council resolutions 1363 and 1373 were not
applicable. However, at present there have been certain considerable state
practices where the right of self-defence was justified against the irregular
armed groups and the non-state actors as well. Such a practice was that of 9/11
and resolution no. 2249 of 20.11.2015 "concerning the activities of the
Islamic State (ISIS) in relation to Iraq and Syria"
, in which the stand of
the Security Council eventually justified the right of self-defence against the
There exists another concern at international stage i.e. whether the acts of
only some certain groups can constitute an armed attack or the irregular,
unarmed actions breaching the sovereignty, by any group can be termed as an
armed attack. Isolated armed actions that take place in border areas cannot be
termed as an armed attack whereas when there occurs an invasion by the armed
forces as done by the ISIS into Iraq from Syria, the requirement of an armed
attack is fulfilled, and the same can be termed as an armed attack.
The attribution to that state, from the territory of which the armed attack is
being carried out, is not necessary. Because, if the territorial state
intervenes and then stops the armed attack, in that case, no issue of
attribution must arise because any attack by the victim state would not be
proportional as the armed attack has already ended. But in circumstances where
the armed attack is in continued, the right of self-defence comes into the
The other major concerns include the term 'armed attack' not being defined by
the UNC. However, the Charter uses the term 'aggression' under article 1 and 39.
Yoram Dinstein has also argued that Article 51 of the Charter purposely uses the
term 'armed attack'
because the concept of an 'armed attack' is more
restrictive than that of 'aggression'.
turns out to be a wider concept that eventually
includes the threat of use of force, but only the threat of an armed attack
cannot trigger and justify the right of self-defence against the originator of
that threat, and that is the very reason that the term 'aggression' has not been
used in article 51 of the Charter. Antonio Cassesse has also stated in his work
that an armed attack must include "massive armed aggression against the
sovereignty, territorial integrity as well as the political independence of a
particular state that imperils its life or government".
In order to support the same, the judgement of Nicaragua v United States must be
taken into consideration in which the ICJ held that "it will be necessary to
distinguish the gravest forms of the use of force (those constituting an armed
attack) from other less grave forms".
Therefore, it is not necessary for an armed attack to be in the form of a
massive military operation. The attacks that occur on a small scale and the 'low
intensity' fights can also be termed or considered as an armed attack as the
actions undertaken by the terrorist groups or insurgents are mostly not in the
form of military attacks but these attacks have the capacity of taking away the
lives of the civilians and military of that state.
In the judgment of US vs Nicaragua of 1986, the International Court of Justice
considered such covert armed actions could be classified as an armed attack if
they are of sufficient gravity. Thus it is valid to say that there exists no
clear threshold of what constitutes an 'armed attack' and it must be decided
from case to case basis whether the level of aggression that is used in that
case, constitutes an armed attack or not.
What Matters Is The Armed Attack And Not The Attacker
It must be argued that the makers intentionally did not mention that the right
of self-defence could only be exercised against the armed attack by a state and
they were wise enough not to exclude the situations where the armed attack has
been carried out by the non-state actors. That is the main reason why article 51
revolves around the victim state and not the attacker. If a particular state
suffers from an armed attack, they have the right to respond irrespective of who
the attacker is.
The initial justification that is also supported by the ICJ decisions in the
Nicaragua case, the Wall advisory opinion and the Congo and Uganda cases, refers
to the law on the responsibility of state especially the imputability of the
non-state aggression acts to the state from where they act. To support the same,
we also need to take article 21 of Articles on State Responsibility that
justifies the measures taken as a right of self-defence and that measures taken
against the originator of armed attack do not constitute the breach of
Self-defence is an inherent right which can be exercised by a state whenever it
faces an armed attack irrespective of the source or from where it originates and
also irrespective of imputability to the third state. Taking the consent from
the third state is not necessary if it has failed to take any preventive measure
to curb the wrongful activities of the non-state actor.
The Security Council has also explicitly stated that "also attacks of non-State
actors, not only those of states, may endanger international peace and security
the measures provided for in Chapter VII including the right to self-defence may
also be taken in case of an armed attack by a non-State actor". Article 51
of the Charter of the United Nations (UN Charter) cannot be viewed in a vacuum,
and it needs to be interpreted in light of State practice.
But there are also certain instances when the host state is, in all possible
ways, unable to take any restrictive action to curb the unlawful actions of the
non-state actor operating from its country as the same happened in Lebanon in
2006, Mali in 2013 and in Somalia in 2008. In that particular case, a state
which eventually accepts its inability to guarantee the international security
and also the internal security of its own state, can lastly fulfil its 'alienum
non laedas' obligation by extending itself to international cooperation. To
summarize the same after considering the present state practices, the exercise
of the right of self-defence can be justified against the armed attack caused by
a non-state actor.
Necessity And Proportionality In The Use Of Force Against Non-State Actors
A lot of hardships have been faced while applying the principle of necessity and
proportionality against the non-state actors. The principle lays down that the
use of force must be in order to destroy or end the threat of attack, i.e. the
use of force must be done only when the attack is ongoing or when there exists
the threat of another future attack.
Now coming to problem that is faced while exercising this right against the
non-state actors is that the armed attacks carried out by these non-state actors
either end and are not ongoing or there exist no imminent threat of attack as
the attacks carried out by these groups may take more than 4-5 years of gap
between the two attacks. But even after looking at this huge time difference,
the imminence of an armed attack can still be proved by taking into
consideration the intent possessed by a non-state actor and also its
capabilities which include the weapons and other assets like the weapons of mass
destruction or the capability possessed by the non-state actor to attack
repeatedly on a state.
The intent can be derived from the statements made by the non-state actors and
irregular armed groups. This capability of the non-state actors can be
diminished by successfully acting in self-defence and curbing the menace of
these non-state actors. Thus, a certain time frame is required with respect to
the action of the defending state while exercising the right of self-defence
against the non-state actor.
And the same has been supported by the statement of Schmitt i.e. the mere fact
that a terrorist group exists leads to the understanding that there will be a
dispute because of there was no intention to continue the violence, the
terrorist group would disband.
The second point is that the use of force must be done only when the other
alternatives, i.e. all the peaceful measures, have been exhausted but the
problem faced with this is that it is almost impossible, in all circumstances,
to indulge in any kind of peace talk or diplomatic relation with the non-state
And even if the state somehow gets in touch with these non-state actors, the
demands possessed by these non-state actors are of extreme ends and the biggest
example of the same was that of Al-Qaeda where their demand to negotiate was the
complete withdrawal of the troops of the United States from the Middle east, and
there should be an end to the support of America for Israel. Hence, the
actions taken by the victim state against a non-state actor must be justified as
the right of self-defence in international law.
The principle of proportionality illustrates that the attack done acting under
self-defence must correspond to the initial armed attack. This is definitely
not to be inferred from this that the weapons and technology used must also be
similar. However, it does mean that the defending state shall only the use
the force that is needed to protect itself must use force that is proportional
to the initial attack.
To conclude, the use of force in self-defence against a non-state actor within
the territory of another state is lawful in cases where the host state or state
providing shelter to the non-state actors (including the terrorist groups) is
unwilling to take preventive measures in order to curb the harmful activities of
these non-state actors. The major concern in most of the circumstances is
whether the activities of a non-state actor can constitute an armed attack or
not and the answer to this is yes, taking into consideration the opinio juris
and scholarly opinion which confirms that the actions of non-state actors can be
termed as an 'armed attack
The victim state after exercising the right of self-defence and responding to
the non-state actors, must inform the Security Council about the measures taken
in order to justify itself and clarify that it intended to target the non-state
The use of force against the non-state actors has imposed a dilemma for the
international law as it can definitely not be expected from the victim state to
not respond to the breach of its sovereignty and the loss of lives in the state.
On the other hand, the right of the host state also needs to be upheld. However,
the state practices have turned this notion in favour of the victim state.
Thus, while exercising the right of self-defence what eventually matters is
whether there has been an armed attack or not whereas the attacker or source is
comparatively irrelevant and that every state has this right of protecting its
sovereignty, territorial integrity and political independence. The limited-time
that a defending state must provide the state from whose territory the non-state
actor operates, depends on the imminence of the threat posed by that non-state
actor. Hence, the right of self-defence under article 51 of the UNC very well
exists against the non-state actors.
- Antonello Tancredi, Doctrinal Alternatives to Self-Defence Against
Non-State, Zaorev de, 2017.
- Brownlie’s Principles Of Public International Law 1090 (James Crawford
eds., 8th ed. 2009).
- U.N. Charter art. 51.
- Michael Wood, Self-Defense Against Non-State Actors – A Practitioner’s
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the UN Charter, (2002) 43 Harv ILJ 42.
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Regarding the Interpretation of Article 51 of the UN Charter?, Zaorev
de (2017) https://www.zaoerv.de/77_2017/77_2017_1_a_15_17.pdf/.
- ICISS (2001) Responsibility to Protect, ¶ 12.
- United Nations Security resolution 1373 (2001), Security Council Counter
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Criteria of the “Unwilling or Unable” Test, Heidelberg Journal of
International Law, 2017.
- S.S. Lotus (Fr. v. Turk.), 1927 P.C.I.J. (ser. A) No. 10 (Sept. 7) ¶
- Corfu Channel, United Kingdom v Albania  ICJ Rep 4 ¶ 22.
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Paddeu, Use of Force against Non-State Actors and the Circumstances
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Wall in the Occupied Palestinian Territory, Advisory Opinion, 2004 I.C.J.
136 ¶ 139 (July 9).
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University Press 3d ed. 2001)
- G.A. Res. 3314 (XXIX), Definition of Aggression (Dec. 14, 1974).
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2015), Cassesse (2005) p.354
- Military and Paramilitary Activities in and against Nicaragua (Nicar. v.
U.S.), Judgement, 1986 I.C.J. 14 (June 27) [hereinafter “Nicaragua case”].
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Notion of International Armed Conflict – Interrelated or Distinct?, Geneva
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- S.C. Res. 1373 (Sept. 28,2001); S.C. Res.1368 (2001).
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Hebrew University, Jerusalem, 5.11.2019, Hebrew University of Jerusalem
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Self-Defence against Non-State Terrorist Actors’ (2007) 56 ICLQ 141.
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- Schmitt (2007) p.175
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