Then perhaps there is a third category: an act of terror.

Why do you have to make it into something else? Just call it an assassination.

While the act may induce terror, it's just confusing to lump it in with attacks against civilians. Attacks against military or para-military or chain of command elements are different because people can choose not to join up or to engage in those professions.

Intelligence agencies have been sending "messages" to one another for decades. It's a known hazard of the job.