Air to Air kill over Raqqa

[Rheinstorff]

Self Defence

In the UK, self defence is an inherent right under the common law, which applies in all circumstances to all people, not just in armed conflict. It's not an issue of LOAC, which deals with the use of force other than self defence. Of course LOAC deals with more than just force, and self-defence is just a shortened way of saying 'self defence and the defence of others'

The issue of re-positioning is, like most issues where force is used, a matter of interpretation of general context and of the specific situation.

So, in Northern Ireland, our adversaries extremely rarely re-attacked, preferring to engage and then escape as soon as possible afterwards. It'd be difficult, when self defence was the prevailing rule of engagement, to justify shooting them in the back as they were running away in the expectation that they would be expected to mount another attack immediately afterwards. The threat to life has passed, the use of lethal force would not be necessary to prevent further loss of life.

However, in Afghanistan, where our adversaries would routinely run away to immediately re-attack, then it would be more justifiable. The threat to life has not passed, so the use of lethal force might be necessary to prevent further loss of life.

With respect to the SU, it's conceivable that repositioning was judged likely - perhaps the Syrian AF undertakes multiple passes - and the presence of weapons may have been too difficult to judge in time limited circumstances. The possibility of an internal gun may have been a factor were no external weapons to have been visible. Additionally, the pilot of the SU might have been capable of directing other aircraft against the ground targets or the F18, even if it had expended all of its own weapons. If this were Syrian AF practice, the SU would likely be a legitimate target.

It's worth noting that US law takes a subtly different view of the imminence of a threat than does the UK law (English and Scottish law are the same on this for all intents and purposes).

As an aside, the term 'Rules of Engagement' is pretty unhelpful. Whilst the 'rules' delegate freedoms on the use of force (within LOAC), they seldom give absolute freedom and most still require interpretation of the situation.