TOKYO (AFP) - The United States is ready to talk to North Korea, Secretary of State John Kerry told an audience in Tokyo, but said Pyongyang had to take "meaningful steps" to honour its international commitments.

"The United States remains open to authentic and credible negotiations on denuclearization, but the burden is on Pyongyang," he said.

"North Korea must take meaningful steps to show it will honour commitments it has already made."

Mr Kerry, whose three country tour of Asia wraps up in Tokyo today after a meeting with Prime Minister Shinzo Abe, said talks in China and in South Korea had already demonstrated the world was talking with one voice.

"One thing is certain: we are united. There can be no confusion on this point," he said.

"The North's dangerous nuclear missile program threatens not only North Korea's neighbours, but also its own people."

He said Pyongyang was bucking the trend of history in its pursuit of atomic armaments.

"At a time when the world is moving toward fewer nuclear weapons, not more - when President Obama has articulated a clear vision for nonproliferation - The last thing we need is one or two states bucking the trend of history and common sense.

"The world does not need more potential for war. So we will stand together, and we welcome China's strong statement of its commitment two days ago to the denuclearisation of the Korean Peninsula."