Are rogue states or non-state actors a greater threat to state security through CBRN proliferation and use?

I am required to write a 3000 words essay (including footnotes, bibliography excluded from word counting) I am studying International Relations, the closest discipline I could choose was Politics. I’ve been previously criticised for not structuring the essay well, using unbalanced arguments and using not too many literature. Therefore, I’d like my essay to be well-structured and to include literatures to support my answer to essay’s question. My lecturers want me to critically engage with the question and find certain gaps in the existing literature that I could make my arguments more convincing. I’d like to have my essay conclude that rogue states (e.g. North Korea) pose a greater threat to state security than non-state actors (e.g. ISIS, Al-Qaeda). (CBRN is an abbreviation used for chemical, biological, radiological and nuclear weapons.)