Beijing also claims the 1.4 million square-mile South China Sea – rich in fisheries as well as undersea oil and gas. In April it entered a tense standoff with the Philippines over rights to part of the ocean. Malaysia, Taiwan, and Vietnam claim all or part of the South China Sea as well.
Then there is the matter of the US being obligated by security pacts or acts of Congress to help defend Japan, Taiwan, and the Philippines – all located off the east coast of rising military power and US cold-war rival China. But today the US also needs China, a low-cost manufacturing base and major market for US exports. An open conflict among disputants could throw US trade, shipping, and naval exercises out of whack.
US officials may be giving leaders of its smaller allied nations in Asia detailed suggestions in private on how to work out differences with China, says Nathan Liu, international affairs professor at Ming Chuan University in Taiwan. “That means the US is going to continue a containment policy from when China was behind the Iron Curtain, but since [China's] opening it needs to make sure they have a voice in international affairs," he says. "They also want to make sure US interests in the region are protected.”
After World War II, when Japan was weak and communist China seen as a threat, the US government gave many former frontline islets to Japan or put them under its own protection.
A 1951 Security Treaty still requires the US to back up Japan during an attack, and a US-Japanese agreement in 1971 gave administrative rights over the eight inhabited East China Sea islets to Tokyo, which calls them the Senkaku. A Mutual Defense Treaty, also signed in 1951, obligates the US to support the Philippines militarily, while a 1979 act of Congress says the US government must consider the defense needs of Taiwan if that island comes under fire.