U.S. Secretary of Mike Pompeo on Monday said negotiations with North Korea could be “one step forward, one step back,” adding that it was difficult to put timelines on the DPRK’s denuclearization.

During an interview with U.S. media on Monday, Washington’s top diplomat also reiterated that despite setbacks, North Korean leader Kim Jong Un had promised to denuclearize.

“President Trump has made clear that there’s no timeline, that this will be one step forward, one step back, perhaps. But I know we’ve made progress,” Pompeo said.

While Pompeo would not be pinned down on numbers or dates, he added that