Researchers at a Defense Ministry think tank say North Korea is developing new ground-to-air missiles, seeking to build an improved air defense system. 

Senior researchers Cho Nam-hoon, Kim Jin-moo and others at the Korea Institute for Defense Analyses issued their latest assessment in a report on Tuesday.

The report said that Pyongyang is constructing an air defense system, citing Kim Jong-un's recent visit to KN-06 surface-to-air antiaircraft missile test launches.

They said that in early May, Kim also ordered officials to further enhance the level of the nation's antiaircraft defense system.