&gt;a foreign &quot;nation&quot; (entity?) attacking another nation&#x27;s<p>IS would be properly categorized as a non-state actor.<p>&gt;It seems a pertinent time to have the debate on what should be done in response, as well as what preventative measures should be taken in the future<p>This is basically one of the main functions of the UN.  While people are free to discuss these things all they like, it would probably be worthwhile to come to the table having an understanding of international law and the use of armed force (i.e. the laws of war).  Though the UN has only existed a brief time, there is plenty of precedent regarding:  when a state may respond to the use of force (from state or non-state actors); what type of response is permitted (i.e. proportional); and what if any preventative measures are permitted.<p>Though there are dozens upon dozens of great case study style textbooks, start here:  <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Use_of_force_by_states" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Use_of_force_by_states</a>