Key: Kim Jong Un an 'unpredictable lone wolf'

Kim Jong Un (AAP)
Kim Jong Un (AAP)

John Key has highlighted North Korea as a major issue of discussion among world leaders at this week's East Asia Summit.

He's taken aim at the country's leader, calling him "unpredictable" and a "lone wolf" in the wake of Kim Jong Un's recent demands to ramp up nuclear force.

The Prime Minister arrived in Vientiane, Laos, on Wednesday and is expected to have a meeting with US President Barack Obama at some stage, as well as several official meetings with ASEAN leaders.

Mr Key says he expects the North Korean leader will be a talking point between himself and Australian Prime Minister Malcolm Turnbull in their bilateral meeting on Wednesday.

"Not only the volume of testing that's been undertaken by North Korea, but also the unpredictability of their leader.

"This is someone that isn't strongly tied into the rest of the world, acts somewhat as a lone wolf but is out there testing on quite a regular basis now, with bigger and more powerful nuclear capability.

"So that will be an issue for regional security and stability."

He says they'll also discuss South China Sea, and Mr Turnbull's discussions with UK Prime Minister Theresa May - how she's feeling about Brexit and how quickly it's going to take place, and the possible free trade agreement with the UK post-Brexit.