Was David Cameron's Syria drone strike legal?

On Monday afternoon, David Cameron made the dramatic announcement that a Hellfire missile fired by RAF drones killed two British nationals in Syria last month, Reyaad Khan from Cardiff and Ruhul Amin from Aberdeen. This is an important moment in British counter-terrorism. Despite 14 years of war in Afghanistan and Iraq since 9/11, this is possibly the first time British forces have targeted and killed British nationals overseas since Gibraltar in 1988.

In some ways, it is surprising that the UK had not yet confronted this problem. The US killed one of its own citizens in one of its very first drone strikes in the Middle East, in Yemen in November 2002. The most prominent case came many years later, when the US authorized the killing of American citizen Anwar al-Awlaki in 2010, killing him in September the next year. Obama administration lawyers argued that the Authorization to Use Military Force (AUMF), a broad resolution passed by the US Congress in 2001, allowed them to target Awlaki, a senior figure in al Qaeda’s Yemen branch, legally. Since then, a number of US citizens have died in American drone strikes, many by accident (including hostages) but some deliberately targeted.

The UK has been here before in a couple of ways. One is the question of whether British intelligence agencies and special forces have supported US-targeted killing, notably strikes in Yemen in 2012. There has been no evidence that British nationals were targeted as part of this, although the fluid intelligence sharing between the US and UK suggests that British information must at least have contributed to some US strikes. We know of some cases where US drones targeted British citizens who had previously been stripped of British citizenship.

Another precedent comes from the Troubles. The most well known case here is probably Operation Flavius, where the SAS shot and killed three members of the Provisional IRA in Gibraltar in 1988. This resulted in a legal case at the European Court of Human Rights, but this concluded that “the shooting of the three suspects could be regarded as absolutely necessary for the legitimate aim of the defence of others from unlawful violence” and that there was no evidence of an “execution plot." Gibraltar is also a British Overseas Territory, so hardly analogous to Syria

The government had stated earlier this summer that it saw no legal bar to intervention in Syria: the Iraqi government had requested help and Islamic State was attacking from across the border. This is known as collective self-defence. It neatly sidestepped the problem of the parliamentary vote against strikes on Assad in 2013, which had merely ruled out action “as part of this campaign." In this legal framing, a British citizen fighting with IS in Syria would be as legitimate a target as if he were fighting with the Taliban in Helmand. If Syria is a legitimate battlefield—on the basis of the collective self defence of Iraq—then IS fighters, British or otherwise, might be considered legitimate targets. It emerged last month that UK special forces reportedly entered Syria as part of a successful US-led raid to capture IS commander Abu Sayyaf. British pilots have conducted strikes in Syria while embedded with US and Canadian forces.

What is interesting is that this is not the argument that David Cameron used in the Commons. Instead, he argued that this was a simple case of self defence against “a terrorist directing murder on our streets” with “no other means to stop him." He underscored this by promising to write to the UN Security Council as required under the UN charter—something that would hardly be necessary if the UK was merely engaging in strikes as routine as those it has been conducting in Iraq. This is similar, though not identical, to the legal approach employed by the US in recent years.

Under the first rationale, the collective self defence of Iraq, Khan could have been targeted merely for fighting with IS. Under Cameron’s argument of basic self defence, the government’s position depends on its claim that Khan was plotting an attack—a claim that it will struggle to substantiate properly without releasing secret intelligence. Given the large number of Britons fighting with IS, some—like Mohammed Emwazi—in highly prominent ones, this is an issue that is sure to recur, even if the government fails to get its way on expanding the broader campaign into Syria.