A former U.S. envoy has urged the Washington to hold talks with Pyongyang without preconditions to break the impasse over North Korea's nuclear weapons and ballistic missile threats.

"I am of the view that the two sides should agree to have 'talks about talks' without any preconditions," Robert Gallucci, chief negotiator for the now-defunct 1994 nuclear freeze struck with North Korea, said in an interview.

Gallucci's view is at odds with U.S. President Donald Trump's policy of imposing "maximum pressure" on North Korea in concert with the international community to compel the hermit country halt its provocative acts and engage in credible talks for denuclearization.