Rudd warns of nuclear North Korea

Kevin Rudd says the most pressing challenge in the Asia-Pacific region is North Korea's nuclear weapons program which must be arrested by a strategy agreed between the US and China.

Speaking on the ABC's 7.30 program on Wednesday the former prime minister said the nuclear threat was the number one priority in terms of US-China relations.

When asked by host Leigh Sales what the pressing challenges were in our region, Mr Rudd said: "I will give you three: North Korea, North Korea and North Korea.

"It's to do with North Korean technical capabilities in terms of missile sophistication, missile range, the availability of nuclear material and the ability to militarise that into a warhead."

The issue was escalating "on a very rapid timescale", said Mr Rudd, who heads up the New York-based Asia Society Policy Institute.

"Therefore the number one priority in terms of US-China relations, leaving everything to one side, is to reach agreement strategically between the president of China and the president-elect of the US into how this can be arrested."

Failing that "the alternatives are too horrible to talk about", he said.

When asked about the "belligerence that Donald Trump is displaying towards China", Mr Rudd said the challenge was to open a channel between the two administrations as early as possible "so the parameters can be set for One China, for North Korea".

He said North Korea was a "sort of freight train rolling down the tracks towards us in terms of its nuclear weapons program".