26 April 2017
The strikes on Syria, in response to chemical weapons attacks on civilians, were politically well-received but contrary to international law – raising difficult questions about the adequacy of the law to prevent atrocities, and how to pursue meaningful reform.

Professor Ben Saul

Associate Fellow, International Law Programme


7 April: US Ambassador to the UN Nikki Haley at a Security Council meeting on Syria. Photo: Getty Images.
7 April: US Ambassador to the UN Nikki Haley at a Security Council meeting on Syria. Photo: Getty Images.


The United States’ recent cruise missile strikes on a Syrian airfield, in response to Syria’s presumed use of chemical weapons (sarin) at Khan Sheikhoun (which killed at least 87 people), were politically well-received by some – but contrary to international law. The US was not acting in self-defence against an armed attack by Syria, pursuant to Article 51 of the UN Charter. The UN Security Council had not authorized military force to restore international security under Chapter VII of the Charter.

Other than self-defence or Security Council authorisation, there are no universally accepted exceptions to the prohibition on military force in Article 2(4) of the UN Charter. There is no right for a state unilaterally to enforce treaties or UN resolutions by military means, whether in response to a breach of Syria’s obligations under two conventions banning chemical weapons (of 1925 and 1993), or a breach of Security Council resolution 2118 (prohibiting Syria from using chemical weapons).

Nor is there any right to use force to halt, deter, or punish violations of international humanitarian law or international criminal law, including the use of chemical weapons. There is no universally agreed wider right of humanitarian intervention against such atrocities. The doctrine of the ‘Responsibility to Protect’ (R2P), endorsed by UN member states, does not create new legal grounds for military intervention, but requires any forcible response to be authorized in the usual way by the UN Security Council.

It may be suggested that the US strikes were ‘illegal but legitimate’, just as NATO’s intervention in Kosovo in 1999 was unlawful but seen by many as morally necessary to prevent atrocities. While a few states denounced the US strikes or questioned their lawfulness, most states refrained from criticism and a considerable number of states – mainly the West and its allies – approved of the strikes. The European Union noted ‘understandable intention to prevent and deter the spread and use of deadly chemical weapons’ and emphasized the strikes were ‘limited and focused’ on that aim.

The strength of an ‘illegal but legitimate’ approach is said to be that it maintains the normative strength of the prohibition on the use of force – avoiding the risks of abuse in widening the permissible use of force – while being responsive to exceptional humanitarian necessities. Its weaknesses include that it is inherently subjective, is open to abuse and mistakes (intelligence assessments can be wrong – as the Chilcott Inquiry into the 2003 Iraq war showed – particularly if force is used prior to any independent investigation), erodes the prohibition on the use of force, and surrenders collective action to unilateralism, inviting self-appointed ‘global sheriffs’.

The US strikes were remarkable for the conspicuous absence of any serious effort by the US or supporting states to reconcile them with international law. The US simply explained that ‘when the international community consistently fails in its duty to act collectively, there are times when States are compelled to take their own action’.

Whether this instance of law-breaking contributes to law-changing – of custom, or treaty interpretation – over time remains to be seen. The legal narratives proffered thus far by states are either too narrow or opaque to instigate meaningful reform.

The incident nonetheless invites, once again, hard questions about the adequacy of international law in the face of atrocities, a problem not resolved by the restrictive doctrine of R2P. It also raises questions about the ability of the Security Council in the present political climate to respond effectively to humanitarian crises.

The strikes are certainly not justified simply because they make us feel good about doing something; or because they assuage President Trump’s proclaimed anguish at seeing child victims on television; or because – as The New York Times crowed – they restored US ‘credibility’ in the world. Why, however, should the use of force still be restricted to the defence of states but not civilians under attack, in cases when the Security Council will not respond, and when military force may be the only feasible means available to avert the harm? Renewed concern for the enforcement of key humanitarian protections in international law is welcome. The perennial question is whether military force without Council authorization can (occasionally) be an appropriate means and if so, where the lines should be drawn.

The debates about humanitarian intervention are well trodden, including the proposed conditions on its exercise – the gravity of harm, force as a last resort (including an absence of peaceful alternatives and the failure of collective action), the use of effective and proportionate means, a reasonable prospect of success, and a right intention.

If the debate is to be reopened, there are immediate threshold difficulties to resolve that are thrown up by this incident. Why bomb to stop the use of chemical weapons, but not the indiscriminate use of helicopter barrel bombs or artillery/rocket/mortar/tank fire – all of which have killed many more in Syria than chemical weapons? Chemical weapons are banned, but so too are indiscriminate means of attack. Why not bomb to halt President Assad’s industrial torture and execution complexes? Why stop at Syria when Sudan, for example, was accused of using chemical weapons in Darfur last year, or when Myanmar continues to ethnically cleanse Rohingya Muslims?

One key question is always whether enlarging the permissibility of uses of force would be effective. In this instance, there are troubling questions about why the US targeted an airfield and aircraft (military targets that can be substituted by the Assad regime) but not the chemical weapons that were the direct source of the threat. And how much force is enough to compel behavioural change? It remains to be seen if Assad will respond favourably.

Another core question is whether enlarging the use of force would cause even more harm than the threat to be averted – such as through escalation, collateral damage, or unforeseen consequences. The use of military force rarely plays out as intended or predicted, as the catastrophes in Vietnam, Iraq, Libya and Syria all demonstrate.

The status quo – of maintaining that the UN Charter rules work except in hard cases – looks increasingly untenable. International law loses legitimacy if it is repeatedly powerless to stop atrocities. Law-breakers who save lives may paradoxically grow in legitimacy, at the cost of the international rule of law.

One modest option for reform would be permit unilateral action in response to a narrowly defined category of threat such as chemical (or biological) weapons, rather than to open the door to the wider, more ambiguous, riskier category of humanitarian intervention.

It is, however, always preferable to strengthen collective responses. Even if it often seems to be a lost cause, it is essential to doggedly pursue Security Council reform. Doing so is the only way to maintain confidence in the law’s legitimacy and thereby to ensure respect for it.

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