Human Rights Watch map of cluster munition strikes in Syria 

The Syrian population has been suffering the effects of conflict for over two years with no end in sight. There has been a massive collective failure by all parties to protect civilians. In the UK and other countries, discussions are now underway about military intervention, most likely in the form of strategic missile strikes. This has been triggered by reports of the escalating use of ememical weapons by Syrian government forces.

The notion that the use of a banned weapon by one country can trigger military strikes by other countries illustrates the political significance of global norms on specific weapons. But any military action to enforce those norms must also adhere to international standards on the means and methods of combat. Moreover, the rush to enforce the chemical weapons norm through military strikes stands in stark contrast to norm enforcement efforts with respect to other opprobrious weapons used by Syria, and may be premature.

Chemical and biological weapons are not the only means and methods of war banned by the international community. Strong prohibition regimes also exist for cluster munitions, landmines and blinding lasers; the use of white phosphorus and other incendiary weapons are carefully regulated. Moreover, an international norm is being promoted that would discourage the use of explosive weapons in populated areas. Syria is in violation of many of these existing and emerging norms. It has been widely criticised by international civil society and progressive states not only for using chemical weapons, but also cluster munitions and explosive weapons in the current conflict.

Article 36 welcomes actions by the international community to condemn all these behaviours and affirm the importance of all these norms. The development and maintenance of global norms prohibiting the use of particular weapons and limiting the use of other weapons in certain contexts is a crucial aspect of protecting civilians. Reaffirming these existing and emerging global norms is the key when they are violated.

That said, affirmation and enforcement of weapons bans need not take the form of military intervention. Such reaffirmation can take the form of condemnation at the international level. It could take the form of an arms embargo, sanctions, or other bilateral or multilateral measures. For example, in relation to the use of explosive weapons, the UK has not condemned this per se, but has called for an end to the use of heavy weapons in population centres. In the case of cluster munitions, the UK condemned their use, as did the US, but did not indicate any consequences for the violation of the emerging global norm prohibiting these weapons. It is not obvious, therefore, why the UK response should be that in order to preserve the global norm against the use of chemical weapons, the UK and others must undertake military intervention.

The United Nations Security Council is of course empowered to legitimise military action to address threats to international peace and security, which could include punishment for the use of outlawed weapons in this case or in others. However an effort to punish a state for using one prohibited weapon would not legitimise the unlawful use of another prohibited weapon. In that sense, it is worrying that one of the reported options for US military intervention in Syria would be the use of Tomahawk cruise missiles, some of which can carry cluster munitions – whose use is widely condemned in the international community.

In its response to the situation in Syria, the UK should condemn the use of heavy explosive weapons in densely populated areas, should continue to reaffirm the emerging global norm prohibiting cluster munitions by condemning their use, and should condemn the use of chemical weapons, which is a violation of customary international law. The UK should also make a commitment that it will discourage the use of cluster munitions by its allies that remain outside the treaty banning them – in this case the US – and should make a commitment that it will not use any explosive weapons with wide area effects in densely populated areas.

These measures would help to strengthen stigmas regarding the unacceptability of different ways of using force and, crucially, would help to ensure that other countries do not add to the civilian suffering already heaped upon the Syrian population.