Global perspective: US-China tension may offer new opportunity for N. Korean diplomacy April 12, 2021 (Mainichi Japan) North Korean leader Kim Jong Un is seen in this file photo. (Korean Central News Agency via Korea News Service) North Korean leader Kim Jong Un, First Secretary of the Workers' Party of Korea (WPK), adopted a policy of "parallel construction of economy and nuclear arsenal" in March 2013, less than a year and a half after the death of his father, Kim Jong Il. At that time, few observers expected the reclusive country's rapid advance in missile development four years later. Following its successful development of a large-scale rocket booster in March 2017, North Korea has test fired medium-range and intercontinental ballistic missiles one after another since May of that year. In November, Pyongyang launched the Hwasong-15 missile that is said to be capable of reaching the east coast of the United States. Kim Jong Un thus declared the completion of the national nuclear arsenal.