US Secretary of State Rex Tillerson has offered reassurance to North Korea that “we are not your enemy”, though he wants help from China to push for conditions that can lead to talks with the North.

He said on Tuesday that the United States does “not seek a regime change. We do not seek a collapse of the regime. We do not seek an accelerated reunification of the peninsula”.

But Tillerson said the US does not think productive talks would result if North Korea came with the intention of maintaining their nuclear weapons.

And he continued to push for Chinese help to keep pressure on North Korea because of their special economic relationship. He said the North Korean problem is not China's fault, but China must help create conditions for productive talks.

The top American diplomat put the onus on Russia to take steps to repair flagging relations with the US, even as he conceded that congressional sanctions would pose a new obstacle. Holding out hope for warmer ties, Tillerson said he would meet with his Russian counterpart within days.

In a wide-ranging assessment of his first six months in office, Tillerson also: revealed the US is looking at options to entice Venezuelan President Nicolas Maduro to leave power peacefully; insisted the US doesn't blame China for North Korea's nuclear behaviour despite the American pressure on Beijing. He said the US is open to talks with Pyongyang; argued that Iran's military must leave Syria for the US to cooperate with Russia on ending the Syrian civil war; named retired Gen Anthony Zinni as special representative to try to resolve the Persian Gulf diplomatic crisis over Qatar.