This appears to be a problem for North Korea. The solution to this pesky moral hazard problem is to force diplomats to "post a bond" in the form of offerring a hostage.
Thae said there was one big obstacle to his defection.
Thae Yong-ho: All North Korean diplomats are forced to leave one of their children back in Pyongyang as a hostage.
Bill Whitaker: As a hostage?
Thae Yong-ho: Yes.
His break came when that policy unexpectedly changed and Thae’s oldest son was allowed to join the family in London. They all agreed to defect. He would not give us the details about his escape and who helped. But we know he was kept in a safe house by South Korean intelligence agents and questioned for more than three months. He said it was too dangerous for us to meet his family.
But if you are going to do it, you must do it continuously.
This is not unlike an alleged criminal posting a bond while awaiting trial or a tradesman posting a bond against faulty repairs.
Suggested by Helen Gorman