The leaders of Vietnam and the Philippines are presenting a united front in their respective disputes with China over territory in the South China Sea. After talks with President of the Philippines Benigno Aquino, Vietnamese Prime Minister Nguyen Tan Dung said, “The president and I shared the deep concerns over the current extremely dangerous situation caused by China’s many actions that violate international law.” He continued,”The two sides are determined to oppose China’s violations and called on countries and the international community to continue strongly condemning China and demanding China immediately end its violations.” Vietnam is considering taking China to an international court over the South China Sea dispute, as the Philippines has already done.“It’s unprecedented for Vietnam to join a U.S. ally and appeal directly for international support,” Carl Thayer, an Australian expert on Southeast Asia, told Reuters. Earlier this month, divisions between members of the Association of Southeast Asian Nations (ASEAN) became apparent when the group failed to mention China directly in its post-meeting statement. Vietnam, which had just confronted China over the oil rig Beijing placed in disputed waters, tried and failed to get the other nations to issue a strongly worded, anti-China joint statement. Vietnam joining forces with the Philippines, Thayer told Reuters, “is an admission that ASEAN is not going to go to the mat on this one, so Vietnam has got to play some of the only options it has got left.”Shortly before the Vietnamese and Filipino leaders concluded their meeting, China’s President warned neighboring countries not to dabble in alliances. “To beef up military alliances targeted at a third party is not conducive to maintaining common security in the region,” he said. In all likelihood, he was speaking indirectly about alliances within the Indo-Pacific region as well as about alliances with the other big fish in the sea—the United States. President Obama, of course, just concluded a whirlwind tour of a number of countries that have territorial disputes with China—Japan, Malaysia, and the Philippines. Afterward, Manila said it hopes the U.S. will help rehabilitate and occupy a naval base on Palawan island just a few miles from disputed islands. In response to the China-Vietnam oil-rig fight, the U.S. Navy asked Vietnam to increase cooperation and welcome U.S. ships back to its shores. In a speech this week, Admiral Jonathan Greenert, the chief of U.S. naval operations, said that he hopes the U.S. and Indian navies will work together in the Western Pacific.To China, this must seem like encirclement. India’s new Prime Minister and Prime Minister Shinzo Abe of Japan are friendly with each other and interested in expanding military cooperation. Vietnam and the Philippines seem to have set aside the territorial disputes and historical disagreements between them in order to put up a united front against China. And the U.S. is striking new naval cooperation agreements with almost everyone who isn’t on China’s side in the battle for the South China Sea. China still has its friends in Southeast Asia, and its coast guard and navy are more powerful than any of its neighbors’ (except probably Japan’s) and only getting stronger.This is one of the hottest spots in twentieth century geopolitics, and don’t you forget it.