Nuclear talks between the United States and North Korea are welcome, but the bullying and threats that led up to them were reckless and it is South Korea that should get credit, the Nobel Prize winning anti-nuclear campaign group ICAN said on Thursday.

Beatrice Fihn, executive director of the International Campaign to Abolish Nuclear Weapons, said U.S. President Donald Trump was not responsible for bringing North Korean leader Kim Jong Un to the negotiating table, since each hostile tweet merely prompted an equally hostile reaction from Pyongyang.

"It's not a very stable way of conducting international relations, by threatening to mass murder a whole country," Fihn told reporters in Geneva.