There have been ripples of criticism in Britain over the Cameron Government's revelation that RAF drones have killed two British nationals in Syria. The strikes that killed Isis (Islamic State) fighters Reyaard Khan, from Cardiff, and Ruhul Amin, from Aberdeen, raised a number of questions, not least about their legality. But do not expect Britons to be protesting in the streets any time soon. Of more resonance to most of them is the threat Isis poses and the usefulness and effectiveness of this relatively new means of waging war.
The strikes marked a substantial escalation in Britain's response to Isis. One trigger for this was the killing of 30 Britons in a terrorist attack on a Tunisian resort in June. Most immediately, intelligence reports indicated Khan was leading a plot to attack VJ Day commemoration services attended by the royal family in London last month. Prime Minister David Cameron said the attack, the first against its own citizens when Britain was not at war, was an act of "self-defence" for which there was a "clear legal basis".
That statement refers to article 51 of the United Nations Charter, which guarantees a nation's right to take pre-emptive action. For that, the need must be "instant, overwhelming, and leaving no choice of means, and no moment for deliberation". There must, in other words, be an imminent threat. Yet the RAF drones struck six days after the VJ Day commemorations. Mr Cameron's way around this was to suggest Khan would never "desist from his desire to murder us at home".
This state of affairs has led to calls for the British Government to release evidence that establishes the threat posed by Khan. Intelligence exigencies mean that will not happen. So does Mr Cameron's knowledge that Britain is crossing territory already traversed by the United States, which has been conducting drone strikes on individuals since 2004 in countries that, in its judgment, lack the capacity to bring them to justice. A long time ago, it abandoned any pretence of meeting the UN guideline. It is prepared to strike without clear evidence of a specific attack on the US in the immediate future - only that a threat is posed to American interests and citizens.
That slippage has attracted little comment in the US. Partly, that is a reflection of the horrific tactics employed first by al-Qaeda and now by Isis. But it also points to the way drones have changed the terms of combat in America's favour.
