The Nuremberg trials were very clear indeed - it is the duty of everybody in the armed forces to refuse toi obey orders to commit a war crime. "I was only obeying orders" is not a sufficient defence. And assassinations such as this would almost certainly be classed as war crimes, if they ever came before a War Crimes Tribunal.

So far as UK law is involved, my understanding is that this principle is incorporated, in theory at least. I am certain that if a case like this were to arise in Britain the government would make sure there was no trial, for fear of the verdict. The interesting thing, if this comes before an Israel court, will be to see if it will uphold this Nuremnbereg principle.