US President Barack Obama has welcomed a bigger role for China on the world stage and pledged to pursue greater co-operation with Asian countries.
Speaking in Tokyo, he said the US would not be "cowed" by North Korea's nuclear threats and that his commitment to the security of Asia was "unshakeable".
Mr Obama also called on Asian leaders to pursue balanced economic growth.
Early on Saturday, he flew to Singapore for an Asia-Pacific economic summit a few hours earlier than planned.
His trade representative Ron Kirk, who is already at the Apec meeting, says the US wants barriers to trade and investment removed to promote an open global trade system.
Mr Obama will round off his week-long Asian tour with stops in China and South Korea.
Calling himself America's first "Pacific president", Mr Obama told the gathering in Tokyo that Washington's commitment to the region's security was "unshakeable" despite fighting wars in Iraq and Afghanistan.
1. Friday 13: Arrived in Japan
2. Saturday 14: To Apec summit in Singapore
3. Sunday 15: Has talks with Russia's President Medvedev before leaving for China
4. Tuesday 17: Summit in Beijing with Chinese President Hu Jintao
5. Wednesday 18: Ends tour in South Korea
He said the US did not seek to "contain" China's rising power, and pledged to pursue "pragmatic co-operation" with Beijing on issues of mutual concern.
"The rise of a strong, prosperous China can be a source of strength for the community of nations," Mr Obama said.
He warned that he would not waver from raising human rights concerns with Beijing, but did not mention specific concerns, such as Tibet.
He sought more assistance from China to thwart the ambitions of North Korea, and warned there would be tough, unified action by the US and its Asian partners if Pyongyang failed to abandon its nuclear weapons programmes.
Mr Obama again called on North Korea to return to six-party talks on the issue.
On the issue of economic co-operation, Mr Obama challenged Asian countries to break their dependence on exports to the US and to pursue "balanced" and sustainable economic growth.
"We must strengthen our economic recovery, and pursue growth that is both balanced and sustained," he said. "We simply cannot return to the same cycles of boom and bust that led us into a global recession."
He said the US would pursue a new economic strategy that would mean "saving more and spending less".
He urged Asian leaders to break their dependence on exports to the US market and to open up their markets to speed up a global economic recovery.
Mr Obama arrived in Tokyo on Friday and met Japanese Prime Minister Yukio Hatoyama.
The two leaders agreed on the need to renew their countries' strained alliance and pledged to work quickly to resolve a dispute over the US military base in Okinawa.
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