It added that the move should lead to a “sure, definite” and “irreversible” commitment to ban nuclear testing.

“Saying is one thing, but until we have a signature and the ratification by the DPRK, to basically solidify the verbal commitment already to cease testing and close the nuclear test site, I think nothing can be for sure, definite, or irreversible,” Lassina Zerbo, Executive Secretary of the UN-partner Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), told the media at a news briefing in Geneva on Wednesday.

“I can only welcome and hope for best.”

He also highlighted that the upcoming talks between United States President Donald Trump and DPRK Kim Jong-Un could present a unique opportunity for a lasting contribution to world peace.

“It might be through this negotiation […] that we open up a situation where the DPRK ratify the Comprehensive Nuclear Test Ban Treaty.”

The Comprehensive Nuclear Test Ban Treaty, or CTBT, bans all nuclear explosions, by everyone, everywhere. It has not yet entered into force despite having been opened for signature and ratification over 21 years ago.

Adopted by the UN General Assembly in 1996, the CTBT is nearly universal with 183 signatures and 166 ratifications.

But 44 specific nuclear-capable nations need to ratify the Treaty before it enters into force. Of these, eight – China, Egypt, India, Iran, Israel, DPRK, Pakistan and the US – are still missing. The last country of the 44 to ratify this treaty was Indonesia, on 6 February, 2012.

Since the Treaty is not yet in force, the CTBTO is officially called the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization.