Washington previously demanded as preconditions a halt to North Korea's nuclear and missile testing, and a demonstration of its will to denuclearize.

"In the past, the United States has generally focused negotiations on halting progress on North Korea's nuclear weapons and missile programs," the report said. "However, several other contentious issues could be included in a prospective negotiation."

Those issues are North Korea's chemical and biological weapons programs, which many analysts say pose a growing threat; North Korea's conventional forces; and confidence-building measures, such as enhancing the transparency of both North Korea and US-South Korea forces to reduce tensions on the peninsula.

The report also listed North Korea's human rights conditions, US detainees in the North, international humanitarian aid, reunions of Korean-Americans and their North Korean relatives, the search for the remains of US soldiers who died in the 1950-53 Korean War, as well as cultural, educational and sports exchanges.

The report, which was prepared for members of the US Congress, detailed past US negotiations with North Korea, from those that led to the 1994 Agreed Framework to the 2012 Leap Day Deal. (Yonhap)