That position was there when we first allowed North Korea to have nuclear weapons.
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.
20 May: North Korea claims to have nuclear weapons capable of hitting the United States.
December: In early December, North Korea leader Kim Jong-un claimed that the country was prepared to detonate a hydrogen bomb, however significant doubts surround the claim.
6 January: North Korea conducts its fourth nuclear test. Although the government claims it to be its first hydrogen bomb, the claim was met with significant skepticism.
6 July: A high-level DPRK Government spokesman’s statement was made defining a more precise meaning of "denuclearization", as covering the whole Korean peninsula and its vicinity, signalling a willingness to continue negotiations on the topic.
9 September: North Korea conducts its fifth underground nuclear test. With an estimate yield of over 10kt, it would make it the most powerful North Korean nuclear test thus far.
26 October: United States Director of National Intelligence James Clapper said during a speech that persuading North Korea to abandon its programme is "probably a lost cause" since, to North Korea, it was "their ticket to survival" and any discussions about ending their nuclear ambitions would be a "non-starter".[73