South Korean ambassador to New Zealand Yongkyu Park addressed about 50 people at the public lecture, organised for the diplomat's short visit to Dunedin this week.
Mr Park said North Korea maintained a "military first" priority, putting its economy at risk.
"North Korea's dilemma is that it has to open up to reform and revive its economy, but opening will threaten its regime, and regime survival is the top priority," he said.
Mr Park also discussed whether North Korea might give up its nuclear weapons, after two decades of negotiating with other nations, but "nobody seems to have the answer ... so far".
Mr Park's lecture included photographs of North Korea's nuclear test sites and rocket launchings.
He said there was much speculation surrounding the country's new leader, Kim Jong-un, and whether his control might herald policy changes.
The young leader's style was different from that of his predecessor, Kim Jong-il, Mr Park said.
"There's a lot of speculation whether this signals fundamental change in policy. It's too early to say, but some believe it could lead to a reformed economy and more liberal political system," he said.
The ambassador planned to meet Dunedin veterans of the Korean War for lunch today before returning to Wellington.
