It is difficult to negotiate with a lunatic. 

We are talking about someone who uses anti aircraft guns to execute his own people. 

https://www.google.ca/amp/www.telegraph.co.uk/news/2017/02/27/north-korea-executed-five-security-officials-anti-aircraft-guns/amp/

https://www.google.ca/amp/s/amp.theguardian.com/world/2016/aug/30/north-korea-reportedly-executes-officials-anti-aircraft-gun-purge