TOKYO – US President Barack Obama on Saturday said Washington would not be "cowed" by North Korea's nuclear threats but said the United States is ready to offer the isolated country "a different future."

"For decades, North Korea has chosen a path of confrontation and provocation, including the pursuit of nuclear weapons," Obama said in a speech in Tokyo during a two-day visit here, his first trip to Asia.

"We will not be cowed by threats, and we will continue to send a clear message through our actions, and not just our words: North Korea's refusal to meet its international obligations will lead only to less security, not more."

Obama urged Pyongyang to return to denuclearisation talks that include the US, Japan, China, the two Koreas and Russia, which it quit in April, before it staged its second nuclear weapons test the following month.

But Obama also said that "there is another path that can be taken", if Pyongyang agrees to the denuclearization of the Korean peninsula.

"Working in tandem with our partners, and supported by direct diplomacy, the United States is prepared to offer North Korea a different future," he said.

"Instead of an isolation that has compounded the horrific repression of its own people, North Korea could have a future of international integration.

"Instead of gripping poverty, it could have a future of economic opportunity -- where trade, investment and tourism can offer the North Korean people the chance at a better life.

"And instead of increasing insecurity, it could have a future of greater security and respect. This respect cannot be earned through belligerence."

Obama also urged North Korea to come clean on the Japanese citizens it abducted in the 1970s and 80s to train its own spies in their language and culture.

"Full normalization with its neighbors can only come if Japanese families receive a full accounting of those who have been abducted," he said.

The parents of Megumi Yokota, a 13-year old schoolgirl kidnapped decades ago by North Korean agents, were present at Obama's speech.

Obama kicked off an eight-day tour in Asia which will take him to Singapore for the APEC summit before he visits China and South Korea.