Which consequence resulted from unresolved international conflicts throughout the 20th century?

The current international nuclear threat of North Korea and development of their ICBM's and nuclear missiles. This is due mainly because we never truly "finished" the international Korean War and only came to a mutual agreement of a cease fire, which resulted in the eventually closing off of North Korea and the creation of the DMZ-which in turn creates the consequence and issues of North Korea being a "rogue state" and the development of their nuclear warheads. Hopefully this helps :)