>>>STATE DEPARTMENT - U.S. Secretary of State John Kerry makes his first trip to Asia next week, where talks in Beijing are expected to focus on an increasingly-aggressive North Korea and on territorial disputes in the South China Sea. China's maritime rivals are pursuing their claims in a variety of ways.

Beijing says its live-fire exercises in the South China Sea are meant to defend against naval and air attacks in the contested waters.

But Vietnam says those Chinese patrols endanger navigation. It says China's navy fired on a Vietnamese fishing trawler near the disputed Paracel Islands.

China says it has done nothing wrong. "The response by the relevant Chinese body against the illegal Vietnamese fishing boat was appropriate and reasonable," said Foreign Ministry Spokesman Hong Lei.

In the South China Sea, Beijing has worked to separate rival claimants, says International Institute for Strategic Studies fellow Christian LeMiere.

"Obviously Vietnam on its own in a bilateral discussion with China is in a very much weaker position.  But if it can gather the support of the U.S. or Japan or India, or at least demonstrate that these states have a stake in the negotiations, then Vietnam will find itself in a much stronger position," LeMiere said.

In its dispute with China, the Philippines is taking South China Sea rivalries to the United Nations while reaffirming old alliances.

"The Philippines is one our our five Asia-Pacific allies, and a very, very important relationship at this point in time when there are tensions over the South China Sea, where we support a code of conduct and we are deeply concerned about some of those tensions and would like to see it worked out through a process of arbitration," said Kerry.

So might Vietnam join the Philippine move to U.N. arbitration? Johns Hopkins University professor Ruth Wedgwood thinks it should.

"To my mind, it would make sense for Vietnam to join them and make it a parallel declaration that the Chinese Coast Guard, whether at the insistence of the Governor of Hainan or whether at the direction of Beijing, really ought not to be pressing each neighbor in the region to withdraw to a three-mile limit as in the olden days. The Chinese are pressing very hard," Wedgwood said.

It is that pressure that makes American University professor Pek Koon Heng believe Vietnam, Malaysia and Brunei will not join the Filipino claim.  She says the legacy of Chinese invasion makes Vietnam especially cautious.

"Something Vietnam does, there is a hugh push back by the Chinese. The Vietnamese understand that there is only so much they can do because over the last ten years, naval modernization by the Chinese has proceeded so quickly," Heng said.

China claims most of the more than three-million-square-kilometer sea from Singapore to the Taiwan Strait -- through which half the world's commercial shipping passes.