Striking Syria: is there international law or is there only power?

Was President Trump legally justified in striking Syria over Assad’s use of chemical weapons?

In February 2014, I was invited by the Brown University International Organization to hold a seminar: Red lines and Game Changers – The Legality of Unilateral or Collective Use of Force in Syria. The topic was inspired by President Obama’s public pronouncement that any use of chemical weapons by the Assad regime would cross a read line, bringing to bear a military reaction by the U.S. with or without approval from the United Nations Security Council (UNSC).

In a White House speech, President Obama expressed his clear intention to use targeted military force to degrade the Assad regime’s ability to use chemical weapons:

This is not a world we should accept. This is what’s at stake. And that is why, after careful deliberation, I determined that it is in the national security interests of the United States to respond to the Assad regime’s use of chemical weapons through a targeted military strike. The purpose of this strike is to deter Assad from using chemical weapons, to degrade his regime’s ability to use them, and to make clear to the world that we will not tolerate their use.1 White House, Remarks by the President in Address to the Nation on Syria, President Obama Addresses the Nation on Syria, 10 September 2013, available at

In his speech to the UN General Assembly, just a few weeks after his White House speech, President Obama struck a different note, appealing to a humanitarian / victim-centered need for collective action:

Different nations will not agree on the need for action in every instance, and the principle of sovereignty is at the center of our international order. But sovereignty cannot be a shield for tyrants to commit wanton murder, or an excuse for the international community to turn a blind eye. While we need to be modest in our belief that we can remedy every evil, and we need to be mindful that the world is full of unintended consequences, should we really accept the notion that the world is powerless in the face of a Rwanda or Srebrenica? If that’s the world that people want to live in, then they should say so, and reckon with the cold logic of mass graves.… I believe we can embrace a different future.2 White House Office of the Press Secretary, Remarks by President Obama in Address to the United Nations General Assembly, 24 September 2013, available at

President Obama’s justifications seemed to vary depending on the target audience: domestically, the message was that action would be taken if chemical weapons were used by Assad for the purpose of degrading and deterring, self-defense, and punishment or reprisals; internationally, it was for humanitarian reasons. When Assad called his bluff, President Obama opted for inaction – for better or for worse.

Whether President Obama chose positive law over natural law, legality over illegality, prudence over imprudence remains an unanswered question.  Scholars and international specialists are divided as to:

(a) Whether under the UN Charter, President Obama could have taken military action against Assad;

(b) Whether under the Responsibility to Protect doctrine (R2P), the US could have legitimately if not legally acted (as was done in Kosovo); or

(c) Whether any military action taken without the express authorization of the UNSC – however laudable the cause – would have been in contravention of the UN Charter and customary international law.

To the victims of chemical attacks these debates are academic and nonsensical. And rightly so.  But does this mean that a nation, because it can act alone and outside international norms (assuming that these norms are exact and not subject to interpretive variances as is not the case here, given the disparate yet compelling positions advocated), should take the initiative?

Some say yes, provided certain conditions are met.3 For example, Sir Daniel Bethlehem, former principal Legal Adviser of the UK Foreign and Commonwealth Office, suggests two distinct justifications for the use of force as humanitarian intervention: a) the weaving threads of law and practice may demonstrate the legality of force outside the UN Security Council system; and b) through a claim that a new norm of customary international law in favor of the principle of humanitarian intervention has rapidly crystallized. See Sir Daniel Bethlehem, Stepping Back a Moment—The Legal Basis in Favour of a Principle of Humanitarian Intervention, Blog of the European Journal of International law, EJIL: TALK! 12 September 2013.  Bethlehem suggests that the legal issues that would have to be considered in the context of Syria situation are: (a) the legal effect of the Security Council’s failure to act; (b) the legal effect that attaches to the use of chemical weapons, as distinct from other massive humanitarian violations that have occurred previously; (c) the legal effect of resolutions of the Arab League; (d) the legal effect of the opposition of Russia, China, Iran and others to the suggestion of intervention. Id. Similarly, Harold Hongju Koh argues that international law has evolved sufficiently to permit morally legitimate action to prevent atrocities by responding to the deliberate use of chemical weapons. See Harold Hongju Koh, Syria and the Law of Humanitarian Intervention (Part II: International Law and the Way Forward), Just Security, 4 October 2013. Others say no, especially if doing so may result in eroding international norms set out by the UN.4 See Anthea Roberts, Legality vs. Legitimacy: Can Uses of Force be Illegal but Justified? Human Rights, Intervention, And The Use Of Force, P. Alston, E. Macdonald, eds., OUP, 2008; Marko Milanovic, Illegal But Legitimate? EJIL Talk! 10 April 2017.

President Trump has yet to clearly articulate the legality of his decision to strike Syria. Considering his rhetoric and affinity for spin, alternative facts, and opportunistic motives, it may be too early to judge whether President Trump is truly committed to working within the constraints of international norms.  Be that as it may, the claims coming out of the White House that this is a one-off (situational) attack for purposes of sending a message to Assad (with more attacks to follow if Assad dares using further chemical weapons to kill Syrians – as opposed to killing them in greater numbers through conventional weapons) are unsatisfying.

Perhaps more clarity will follow in the days, weeks, and months ahead.  So far, this strike has accomplished little, if anything.  The situation on the ground in Syria is highly complex, and, like President George W. Bush, President Trump does not seem to do nuance.  And of course, when considering the controversies surrounding his administration and his affinity for governance by chaos, it is hard not to be cynical and presume that his actions against the Assad regime were more about detracting from the various scandals, investigations (Russia-gate), and policy failures than they were about Assad’s use of chemical weapons. Time will tell.

My position when President Obama drew the now-infamous red line was that any unilateral action taken by the US, be it for degrading and deterring, self-defense, and punishment or reprisals, or for humanitarian purposes, does not seem to be legally or legitimately justified.

Article 2(4) of the UN Charter provides only two exceptions to the general prohibition on the use of force: 1) self-defense and 2) UNSC authorization. Article 51 of the Charter preserves the inherent right of individual or collective self-defense, “if an attack occurs against a Member of the United Nations.” The trigger for the use of force in self-defense is thus the occurrence of an “armed attack.”

There is an argument that pre-emptive self-defense (distinguished from anticipatory) is lawful under customary international law, stemming from Caroline affair.5 See Donald R. Rothwell, Anticipatory Self Defence in the Age of Terrorism, 24 U. Queensland L.J. 337, 339 (2005). In 1837, the British seized the Caroline, a ship which had been used by American rebels for armed raids on Canadian territory. The ship was set on fire and sent over Niagara Falls, resulting in the death of two US nationals. The US Secretary of State asserted that Britain would need to show “a necessity for self-defence, instant, overwhelming, leaving no choice of means, and no moment for deliberation.” The second element would be that the use of force in self-defense must not be excessive, and “must be limited by that necessity and kept clearly within it.”  Under pre-emptive self-defense, the use of force can be justified if it is necessary to avert an imminent attack, provided that the use of force is proportional.6 See Donald R. Rothwell, Anticipatory Self-Defence in the Age of International Terrorism, 24 U. Queensland L.J. 337-354 (2005), analyzing the anticipatory and pre-emptive self-defense. Thus, if Syria’s possession and/or use of chemical weapons would give rise to a certainty that ISIS would come into possession of chemical weapons (obviously Assad has not disposed of his stockpile as he was required under the negotiated agreement between the US and Russia)7 The Organisation for the Prohibition of Chemical Weapons, Joint National Paper by The Russian Federation and The United States of America, Framework for Elimination of Syrian Chemical Weapons, EC-M-33/NAT.1, 17 September 2013, Annex “Framework for Elimination of Syrian Chemical Weapons, dated 14 September 2013”, available here. According to the joint framework on destruction of Syrian chemical weapons, the Russian Federation and the United States are to “work together closely, including with the OPCW, the UN and Syrian parties to arrange for the security of the monitoring and destruction mission, noting the primary responsibility of the Syrian government in this regard.” Id., Annex B. On the same day after the Framework was agreed and signed, Syria announced that it was acceding to the Chemical Weapons Convention, formally taking effect on 14 October 2013. then arguably this could trigger a justification for a lawful anticipatory or – as nuanced by Prof. Yoram Dinstein – an interceptive strike to counter an imminent and practically unavoidable attack.8 Professor Dinstein makes a distinction between pre-emptive self-defense and interceptive self-defense. A pre-emptive strike anticipates an armed attack that is merely “foreseeable,” while an interceptive strike counters an armed attack that is “imminent” and practically “unavoidable.” See Yoram Dinstein, War Aggression and Self-Defence 219 (3rd ed., CUP 2001). But this is not a justification or a motive claimed by President Trump. There is no recognized right of pre-emptive or anticipatory self-defense, where an armed attack is not imminent.9 Military and Paramilitary Activities in and Against Nacaragua (Nicar. v. US), 1986 I.C.J 14, para. 92 (June 27). Although anticipatory self-defense was not discussed in the case, the International Court of Justice did not extend the right of self-defense under Article 51 of the Charter, a claim advanced by the United States, to enable the US to provide assistance to rebels in a non-international armed conflict.  The strike doesn’t fit even the most extended form of self-defense.

Any other potential uses of force must be authorized by the UNSC. Under Article 24(1), the UNSC has the “primary responsibility for the maintenance of peace and security.” Binding measures, including the use of military force, under Chapter VII may be imposed only if there has been a “threat to peace, breach of peace, or act of aggression.”10 UN Charter, Art. 39. There is no legal framework covering situations if the UNSC is deadlocked by the veto of a P-5 member.  Maintaining peace and security is not the only one purpose of the UN as the UN Charter contains elements of human rights and humanitarian principles.11 As stated in the UN Charter Preamble, other purposes of the UN are: “to save succeeding generations from the scourge of war…to reaffirm faith in fundamental human rights, in the dignity and worth of the human person….” However, there is no explicit right of intervention for humanitarian purposes. Under present international law, there seems to be no justification for the use of force outside self-defense or UNSC authorization. (For more analysis on justifications of unilateral use of force, see my post on Red Lines and Game Changers here.)

Rigid as this position is, I remain unconvinced that customary international law has progressed since 2014 such that it would justify President Trump’s Syrian strike – limited as it was and even if motivated for pure reasons.  This does not mean that I am any less conflicted: inaction is certainly not an acceptable option.  Something needs to be done in Syria, but a limited one-off strike to send a message as opposed to a collective effort by UN Member States is not the answer.

Wherever one finds himself or herself in this debate, the one positive result from the US’s strike in Syria concerning Assad’s use of chemical weapons is that there is a lively debate among scholars and policy makers about the need for greater clarity in what is an acceptable response by States, individually or collectively, when a regime commits mass atrocities.  Of the many interesting blogs posts that have been circulating the past few days, I particularly recommend: Syrian Strikes: A Singular Exception or a Pattern and a Precedent? by Anthea Roberts; US Strikes against Syria and the Implications for the Jus ad Bellum by Monica Hakimi; Illegal But Legitimate? by Marko Milanovic on EJIL Talk!, and I agree with Harold Koh by Jens David Ohlin on Opinio Juris.

About Author



Author: Michael G. Karnavas

Michael G. Karnavas is an American trained lawyer. He is licensed in Alaska and Massachusetts and is qualified to appear before the various International tribunals, including the International Criminal Court (ICC). Residing and practicing primarily in The Hague, he is recognized as an expert in international criminal defence, including pre-trial, trial, and appellate advocacy.

One thought on “Striking Syria: is there international law or is there only power?”

  1. Thanks Michael for that comprehensive and well organized analysis , by itself presents too many complications , yet , one point has gone missing :
    You put super powers and ordinary states , at the same level , but , it is hard to accept it . The SC is effectively non effective body , without consent of super powers . The philosophy is very simple : if super powers support a resolution , it does express more effectiveness and enforcement of the discussed resolution , and , the CIL in fact .

    So, super powers have more power, more rights, yet, more obligations. Now , the short history of the war in Syria , suggests clearly , that Russian Veto is guaranteed , and above all , Russian itself , is deeply implicated there .

    So, we have a grave violation of jus cogens (chemical attack) and no remedy (The veto is guaranteed).

    That is how , new CIL ( effectively ) is developed !! otherwise , never ever , new CIL doctrine shall be implied , and enforced . CIL , is not only sheer numbers of states defining it , means : quantity , but also quality :
    Jus cogens , and super powers conduct . In this regard , it is justified !! If not in reaction and retaliation to such jus cogens , then , when exactly ?? Shall we wait for reform in the structure and protocols of the SC ?? We won’t stay young !!


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