Donald Trump has threatened Syria with a ‘big price to pay’ for an alleged chemical attack on 7 April in a Damascus suburb. Last year, in similar circumstances, Trump authorized an attack of 59 Tomahawk missiles that reportedly killed 9, including 4 children. The French and German governments responded with a joint press release finding it a ‘just and proportionate’ response. They did not say ‘lawful’–nor could they.
Armed reprisals are uses of military force that follow an incident, usually to punish or in retaliation or revenge and which do not fit the exception to the prohibition on the use of force for self-defence. See the same conclusion here and here. Reprisals need Security Council authorization to be lawful. The Security Council has never authorized a reprisal and will not in the case of Syria.
In 1970, the General Assembly stated clearly in its Declaration on Principles of International Law Concerning Friendly Relations and Cooperation among States that among the fundamental rights and duties of states, is the ‘duty to refrain from acts of reprisal involving the use of force’ against other States. The International Court of Justice found in its 1994 advisory opinion on the Legality of Threat or Use of Nuclear Weapons that ‘armed reprisals in time of peace […] are considered to be unlawful.’ In the Oil Platforms case, it further held that US attacks on Iranian sites were not lawful acts of self-defense because of their retaliatory nature.
Thus, unauthorized reprisals are always unlawful Read the rest of this entry…