Han Tae Song, North Korea’s Ambassador to the UN, told the Conference on Disarmament last year’s nuclear test allowed his country to “perfect a national nuclear force” in a transparent manner.
“Thus DPRK [North Korea] at last came to possess a powerful and reliable war deterrent,” he told the Geneva forum.
“I am proudly saying that DPRK’s nuclear force is capable of frustrating and countering any nuclear threats from the US and it constitutes a powerful deterrent that prevents the US from starting an adventurous war.”
He went on to add that as a “responsible nuclear power”, North Korea would not use its nuclear weapons unless foreign states violated its sovereignty or interests.
In response, US disarmament ambassador Robert Wood said Washington would never recognise the secretive country as a nuclear power and told Pyongyang exactly what it must to to be welcomed back to the international community.
He said: “The United States will not recognise North Korea as a nuclear weapon state.
“If the North wishes to return and be in the good graces of the international community, it knows what it has to do, it has to take steps toward denuclearisation of the Korean peninsula.”
In an earlier speech on Tuesday, United Nations disarmament official Izumi Nakamitsu welcomed an easing of tensions between North and South Korea but called for further steps towards removing nuclear weapons from the divided peninsula.
Meanwhile, North Korea’s UN ambassador accused the US of deploying military assets nearby under the pretext of ensuring the security of the Winter Olympics.
He said: “This is dangerous act of throwing a wet blanket over the current positive atmosphere of inter-Korean relations… which could drive again into an extreme phase of confrontation.”
The news comes amid a notable thawing of the hostile relations between North and South Korea, with the two countries agreeing to march under a unified flag during the opening ceremony at next month’s Winter Olympics.
Officials reopened the hotline between the two countries this month, which had not previously been used since December 2015.
Lee Hee-beom, the Winter Olympics organising chief, previously raised the possibility of the two Koreas forming unified teams in figure skating and ice hockey for the Games to be held in the mountain village of Pyeongchang, just 50 miles (80km) from the inter-Korean border.
The two Koreas have competed as a single nation in sports events before, including football and table tennis matches, but have never joined forces for a major event such as the Olympics or the Asian Games.
The countries even marched together at the Sydney Olympic Games in 2000 after North and South Korea held their first ever summit, but relations have since soured.
North Korea has, however, participated in the international multi-sports events hosted by South Korea three times – in 2002, 2003 and 2014.
Until this month, the two countries had not conducted high-level talks for more than two years.