The North Korean nuclear program can roughly be divided into four phases. Phase I (1956 -- 80) dealt primarily with training and gaining basic knowledge. Phase II (1980 -- 94) covers the growth and eventual suspension of North Korea 's domestic plutonium production program. Phase III (1994 -- 2002) covers the period of the "freeze '' on North Korea 's plutonium program (though North Korea pursued uranium enrichment in secret) and Phase IV (2002 -- present) covers the current period of renewed nuclear activities.
when did the north korean nuclear program start
1956