Over the weekend, North Korea’s government accused U.S. administration officials of using “gangster-like” diplomacy methods to push for the former country’s move toward denuclearization.

Secretary of State Mike Pompeo responded to these claims by saying other nations and organizations like the United Nations have previously used similarly aggressive methods to try to get authoritarian regimes like North Korea’s to denuclearize, by imposing sanctions or in other ways.

“If those requests were gangster-like, the world is a gangster,” Pompeo said Sunday“When we spoke to them about denuclearization, they did not push back. The road ahead will be difficult and challenging and we know that critics will try to minimize the work that we’ve achieved.”

North Korean government-run news outlet KCNA made the original comment on Saturday. Just one day earlier, officials from the country had said negotiations with Pompeo turned out “concerning” and “regrettable.” Pompeo, on the other hand, seemed to strike a positive tone when discussing the talks.

The state of U.S.-North Korea relations has been uncertain ever since the historic nuclear summit Kim Jong-Un and President Donald Trump held in Singapore on June 12. The two leaders appeared to have gotten along quite well —despite holding a very tense and bitter relationship last year — although the meeting was criticized for its lack of details, among other reasons. Many American news outlets also said it seemed as if Trump had made major concessions to North Korea while receiving very few promises in return. After the summit, Trump alleged North Korea was “no longer a nuclear threat.”

SLIDESHOW: DONALD TRUMP’S 30 CRAZIEST TWEETS

On Saturday, Pompeo posted a photo on Twitter of him meeting with Korean and Japanese officials.

Recent reports have claimed North Korea is still increasing its nuclear arsenal.