Because one of the 3 basic principles of sovereignty (as is understood by western political philosophy, known as Westphalian sovereignty) is that there is no other authority inside a State’s borders except its own.
This means no other country has jurisdiction in North Korea, besides, there’s also no incentive to help in case DPRK asks for help.
France doesn’t investigante crimes that happen in Spain, Portugal doesn’t investigate crimes that haven in Canada, the USA doesn’t investigate crimes that happen in Germany, etc…
This means no other country has jurisdiction in North Korea, besides, there’s also no incentive to help in case DPRK asks for help.
France doesn’t investigante crimes that happen in Spain, Portugal doesn’t investigate crimes that haven in Canada, the USA doesn’t investigate crimes that happen in Germany, etc…