'Police officers are not legitimate military targets. They are of course a very common target in many conflicts, and such attacks are generally recognised as terrorist acts, whoever carries them out'.

Moot point. The Royal Irish Constabulary (and, after 1922, the Royal Ulster Constabulary) were constituted as a centrally-controlled armed force, outside of the nominal local, civilian control which governed policing in the rest of the UK (apart from the Met, which falls under the Home Office). Indeed, the RUC was the only UK police force whose budget and establishment were included in the United Kingdom Statememt of Defence Estimates (the annual publication which outlines British military spending for the upcoming year). Not that I'm condoning or advocating killing coppers, but in the case of Northern Ireland the distinction between the military and civilian security apparatuses (apparati?) is (or was) something of a false one. That is, I would think, even more so in heavily-militarised parts of the world like the Middle East.