The former top North Korean nuclear negotiator Sunday delivered a scathing indictment of the United States' position in nuclear talks, blasting Washington's "delaying tactics" and warning of a failure to heed leader Kim Jong Un's deadline for a "bold decision" by the year's end.

Senior North Korean official Kim Yong Chol, a known regime hard-liner, said in a statement carried by the official Korean Central News Agency that "no substantial progress has been made" in improving ties and that continued "belligerent relations" could lead to an "exchange of fire" at "any moment."

Kim Yong Chol said the U.S. would be "seriously mistaken" if it ignores the end-of-the-year deadline by using "delaying tactics" and "exploiting the close personal relations" between President Donald Trump and the North Korean leader.