Kurt Campbell, the former top U.S. diplomat for Asia, told reporters at a forum in Seoul that there was substantial concern with the way Pyongyang has treated what was supposed to be a venue to improve inter-Korean relations.

NPR: Most South Koreans Leave North Korean Factory

The new South Korean government has separated humanitarian aid from nuclear weapons negotiations, and President Park Geun-hye has patiently held out an olive branch in the form of her "trustpolitik" policy, which promises step-by-step efforts to stabilize inter-Korean relations.

CNN: Why North Korea regime is scary