US President Barack Obama said on Tuesday that he will raise maritime territorial issues in October at the East Asia Summit and the first US-ASEAN summit.
Keeping "moderate tensions" between nations in the region will help the US strategy in the Asia-Pacific, experts said, adding that Washington will avoid confronting Beijing directly on territorial issues.
Obama also said that the Association of Southeast Asian Nations, the US and China will for the first time conduct joint exercises on disaster and humanitarian relief.
The US president made the announcement after meeting with Sultan Hassanal Bolkiah of Brunei at the White House. Brunei holds the rotating presidency of ASEAN and will host the October summit.
"We'll be discussing maritime issues," Obama told reporters.
"Obviously, there have been a lot of tensions in the region around maritime issues, and his majesty has shown great leadership in trying to bring the countries together to make sure everybody is abiding by the basic precepts of rule of law and international standards so that conflicts can be resolved peacefully and effectively, and that everybody is brought into that kind of structure."
The East Asia Summit was inaugurated in 2005. Obama became the first US president to attend a summit, in Indonesia in 2011. He also took part in the 2012 meeting in Cambodia.
Maritime tensions have risen in the past two years between China and some neighboring countries, including the Philippines and Vietnam in the South China Sea, and Japan in the East China Sea.
China has long maintained that the territorial disputes are bilateral matters between individual nations. Yet Japan and some ASEAN countries have turned to Washington for support.
The US said it does not take sides in the disputes. But it sent aircraft carriers to the region to protect "navigation freedom", although Beijing said freedom of navigation has never been a problem.
US Secretary of State John Kerry also reaffirmed to Japan's foreign minister in February that the Japan-US Security Treaty applies to the Diaoyu Islands.
On Wednesday, Japan called for stronger security ties with Southeast Asia, as vice-minister level representatives from Japan and the 10-member ASEAN began a two-day gathering in Tokyo.
"The Asia-Pacific region has various issues concerning security and defense, including territorial conflicts in the South China Sea," Japan's Deputy Defense Minister Akinori Eto said at the opening session.
"On top of the growing maturity of our economic cooperation, Japan and ASEAN need to further strengthen ties in the field of security and defense," Eto said.
The meeting is the first high-ranking defense dialogue of its kind since hawkish Japanese Prime Minister Shinzo Abe took office in December.
"Our country changed governments late last year," Eto said. "Under the new one, we want to reinforce cooperation in security and defense with ASEAN countries and contribute to peace in the region," he added.
AFP contributed to this story.
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