The UK has been carrying out drone strikes on targets in Syria. One of the targets was a man from Cardiff, Reyaad Khan. This was initially justified by the Prime Minister as based upon the UK’s inherent right to self defence. There was said to be evidence of the individuals killed planning and directing attacks against the UK.
Some commentators, notably Joshua Rozenberg and Carl Gardner, thought that this action by the UK could be justified on this basis, under Article 51 of the UN Charter. Although this is possible, it is for the reasons given by David Allen Green, doubtful. Pre-emptive acts of self-defence are possible, but only where the need is “instant, overwhelming, and leaving no choice of means, and no moment for deliberation.” We cannot know for sure without more facts, but it seems unlikely that these conditions could all be met in relation to those killed.
There is however an easier route to provide a legal justification for the UK’s actions. This involves invoking Iraq’s right to self defence, rather than the UK’s. The argument proceeds as follows.
1. Iraq is entitled to act in self defence against those attacking it (ie Daesh). These attacks are current and all too real: there is no need to rely upon any argument based upon pre-emptive action.
2. The UK is acting under the Iraqi government’s request and authorisation. The UK has the same freedom of action as Iraq does as a result.
3. Military action against Daesh in Syria is legal because the Syrian government has proven “unable or unwilling” to stop military action against Iraq from their bases there. This is well explained by Carl Gardner here.
4. The people killed were acting for Daesh in Syria as part of the ongoing conflict against Iraq. Their deaths were therefore lawful.
5. If they were planning terrorist attacks in the UK, that provides an incidental benefit for their deaths, but not the proximate legal justification under public international law.
In a letter to the United Nations Security Council, the UK’s ambassador Matthew Rycroft now invokes this argument to justify the air strikes (see the third paragraph in particular). This seems correct.
Two objections have been made to this analysis.
First, didn’t the UK Parliament vote against military action in Syria? This is a political, not a legal argument, and doesn’t impact upon the legality of the UK’s actions under international law. Even so, the UK Parliament voted against military action against the Assad regime (which would not have been justified under international law), not airstrikes against Daesh (which are justified under international law).
Second, Carl Gardner asks whether this justification could work if the targets were not acting against Iraq at all, but were merely plotting UK terrorist attacks? As such terrorist planning would be undertaken in order to deter the UK from giving the Iraq government military assistance, that would make such activity a legitimate military target for Iraq, and consequently for those authorised to act on Iraq’s behalf (ie the UK).
The human rights of those killed is a separate question. Unlike the (in)famous killing of the three IRA terrorists in Gibraltar, these Daesh fighters were killed lawfully in a war, the UK operating for the the Iraq government in its defence,
The conclusion is that these deaths were lawful, but that does not mean that the UK has the legal freedom to assassinate potential terrorists wherever they may be in the world.