US President Barack Obama dove into the tumultuous diplomatic waters of the West Philippine Sea (South China Sea) on Tuesday at a summit dominated by rival claims to the strategically vital area.

Obama expressed concerns about the disputes between Beijing and its Southeast Asian neighbors such as the Philippines, which have stoked tensions across the region this year and hampered efforts to foster economic cooperation.

The US president is on the final leg of a three-nation trip to Asia aimed at deepening Washington’s influence in the region and countering the rise of China.

Both he and Chinese Premier Wen Jiabao are among the leaders of 18 nations in the Cambodian capital, Phnom Penh, for the two-day East Asia Summit, and the pair were set to hold bilateral talks on the sidelines of the gathering.

Wen insisted on Monday that the maritime disputes should not be “internationalized” and discussed at multilateral events such as the summit. Philippine President Benigno Aquino 3rd, on the other hand, has insisted that Manila wants to discuss the maritime disputes on a global stage.

China, which claims sovereignty over virtually all of the sea, prefers to negotiate directly with its neighbors from the 10-member Association of Southeast Asian Nations (Asean).

But Obama and Asean leaders agreed in a meeting on Monday to support a regional code of conduct to manage disputes over claims in the area, said a joint US-Asean communiqué.

President Aquino, meanwhile, stressed the need to include other countries like the US in the discussions.

“It is especially vital to have the world’s largest national economy involved in the discussions considering the interconnectedness of our current milieu. Each one of our nations has a stake in the stability of Southeast Asia. The United States understands this and, for this reason, has chosen to work with us to ensure the peace and continuous advancement of our region,” the President said.

Aquino, however, is confident that the United States would not take sides in the issue of competing claims in the West Philippine Sea.

“The US won’t take sides with regards to the disputes but they do have an interest in freedom of navigation, freedom of communication, stability in the region,” he said.

Asean members Vietnam, the Philippines, Malaysia and Brunei, as well as Taiwan, also have claims to parts of the sea, which is home to some of the world’s most important shipping lanes and believed to be rich in fossil fuels.

The rival claims have for decades made the sea a powder keg issue in the region. Chinese and Vietnamese forces engaged in clashes in 1974 and 1988, in which dozens of troops died.

After a long period of relative calm, tensions have risen over the past two years with the Philippines and Vietnam expressing concerns that China is becoming increasingly aggressive in staking its claim.

Some bruising diplomatic confrontations this year have overshadowed regional meetings where the participants typically prefer to focus on improving economic ties.

Mr. Aquino said that he is pleased over the progress of discussions by Asean member-countries that may lead to the crafting of the code of conduct (COC) in the West Philippine Sea.

In an interview with the Philippine media in Cambodia, the President said that he is happy that efforts to start the formal discussion for the crafting of the COC, which is believed as a step toward the resolution of territorial disputes in the area, is now gaining momentum among the Asean member-countries.

“The significant development is that there are now discussions, informal talks on the COC. The COC is, of course, the Code of Conduct that will implement the DOC or the Declaration of the Conduct of Parties in the South China Sea,” President Aquino said.

Asean countries, and also China, agreed 10 years ago on the Declaration of the Conduct of Parties in the West Philippine Sea.

Aquino said that now, more Asean members are calling for formal talks to draft the COC, including countries that have no claims in the disputed islands in the West Philippine Sea.

Likewise, the President said that there was progress in this month’s summit, unlike last July’s discussions among Asean foreign ministers, which ended without a joint statement about the disputes.

“There is a consensus to discuss it formally. We are nearing the point of the crafting of the rules, which will tell everybody what is expected of them, what they can do, what they cannot do that promotes stability that is for everybody’s interest,” he added.

The Philippines envisions a code of conduct that will bind it and West Philippine Sea’s other claimant states: China, Taiwan, Vietnam, Malaysia and Brunei.

This, President Aquino said, is like an enabling law that will concretize the principles of the 2002 DOC of Parties in the West Philippine Sea.

WITH A REPORT FROM CATHERINE S. VALENTE