Obama: North Korea's isolation means less leverage in talks

Former President Barack Obama said today that negotiations with North Korea on its nuclear weapons programme are difficult, partly because the country's isolation minimises possible leverage, such as trade and travel sanctions against Pyongyang.

"North Korea is an example of a country that is so far out of the international norms and so disconnected with the rest of the world," Obama told a packed hall in Tokyo.

He stressed the effort to get North Korea to give up nuclear weapons remains difficult, but countries working together, including China as well as South Korea and Japan, to combine pressure on North Korea will be better than nations working alone.

He noted that past US efforts on Iran's nuclear weapons were more successful because there was more leverage, but there's little commerce and travel with North Korea to being with.

"That makes them less subject to these kinds of negotiations," he said of North Korea.

Obama was speaking at an event sponsored by a Japanese nonprofit group during his trip to Asia, which included earlier stops in Singapore, New Zealand and Australia. Obama's work after leaving office has been focused on nurturing young leaders.

Obama, welcomed by a standing ovation, said the US-Japan alliance remained strong, and the US committed to defending Japan.

"North Korea is a real threat," he said.

"Our view has always been that we would prefer to resolve these issues peacefully," he said, adding that otherwise "the cost in terms of human life would be significant."