* China has growing blue water fleet, U.S. adding ships
* Lack of communication between Chinese, U.S. navies
* China more assertive in making maritime claims
By Ben Blanchard
BEIJING, Aug 17 (Reuters) - The game of military bluff that China and the United States are playing off the Chinese coast could erupt in full-fledged crisis hitting the arteries of global trade if Pentagon worries about missteps ever come true.
China has been investing big slices of its growing wealth in modernising its military, and turning its once creaky navy into a blue water fleet that can project power far from its shores, with nuclear submarines and, maybe one day, aircraft carriers.
China is sending naval vessels further afield, to the waters off Somalia to fight pirates, and most recently through the southern Japanese islands, to Tokyo's angst.
That also worries Washington, the world's dominant power, which keeps a hefty military presence in the Asia-Pacific.
While war between the two economically intertwined powers remains a remote possibility, the Pentagon warned on Monday of risks of "misunderstanding and miscalculation" getting out of hand in this trade-driven part of the world plied by thousands of ships daily carrying cargo and oil.
"The U.S. military and the Chinese military don't have a common understanding, a rules of the road, for navigation. That's a major cause for concern," said Drew Thompson, a China expert at the Nixon Center in Washington.
The United States for its part has moved advanced attack submarines and warships to bases in Japan and Guam. It has shown no sign of giving up surveillance missions in what it considers international waters and which infuriate Beijing.
Through missteps or miscalculations, the shadowing and jostling between the two sides could flare into a crisis drawing in other governments around the region and rattling investors who fear discord between Beijing and Washington.
The past few years have seen a number of incidents between the two sides, most seriously in 2001, when a U.S. spy plane made an emergency landing on Hainan after a collision with a Chinese fighter jet over the South China Sea. China released the 24 crew after a U.S. apology and a tense couple of days.
With the two militaries not speaking after Beijing cut off contacts over U.S. plans to sell arms to Taiwan, the self-ruled island that China claims as its own territory, the risk of something bad happening is now elevated further.
"The biggest potential for conflict between China and the United States is in a naval face-off," Wang Jisi, a prominent international relations professor at Peking University, said recently, according to a Chinese current affairs magazine.
"The United States is increasing its surveillance and patrols. As neither have established crisis prevention or management systems, a military clash could morph into a political crisis."
Now Beijing is making noise about the contested South China Sea, long claimed by China, along with Vietnam, Taiwan, Malaysia, the Philippines and Brunei, and has been incensed by U.S. comments on the problem last month.
China's determination in asserting sovereignty over the strategic waterway and its scattered atolls, located on major shipping lanes and potentially rich in energy reserves, has unnerved southeast Asia.
"The threat of conflict is elevated, and the fundamental reason is that China's attitude toward the Eastern Sea has grown stronger by the day, more defiant," Duong Danh Dy, a former Vietnamese diplomat and China expert, told Reuters.
The Eastern Sea is Vietnam's name for the South China Sea.
A U.S. aircraft carrier visited Vietnam this month in a show of force to remind China that Washington will safeguard the right to free navigation in the sea, through which flow oil imports to the economies of Japan, South Korea and Taiwan.
"We all have a right to operate here together and not at the exclusion of anybody else. These waters belong to nobody, yet belong to everybody," Captain David Lausman of the USS George Washington told reporters as F-18s catapulted into a grey sky.
But Beijing believes that its neighbours and Washington will have to get used to dealing with a more assertive China.
Xu Guangyu, a retired People's Liberation Army major general and now a researcher at the China Arms Control and Disarmament Association, said the country had to become firmer on stating its claims as its maritime interests have grown.
"We were once the sick man of Asia, and now our health is returning. This may make some people abroad uncomfortable and lead to misunderstandings," he told Reuters.
China has also been angered by joint U.S.-South Korean naval exercises, ostensibly aimed at deterring North Korea, but which Beijing sees as happening too close to home for comfort.
Chinese media has been shrill in their denunciations.
"The United States appears to want to declare to the world, 'The Asia-Pacific and the oceans remain under the United States'," Communist Party mouthpiece the People's Daily said in a commentary on Tuesday.
But ultimately China is likely to pull back from any showdown over military influence. Outright confrontation would shake China's own economic prospects, which the ruling Communist Party sees as key to social stability and keeping itself in power.
"The prospect for these higher political tensions perhaps raises the stakes, but I don't think that the senior Chinese leadership is looking to manufacture or instigate an incident," said Thompson, the researcher at the Nixon Center. (Additional reporting by Chris Buckley, and John Ruwitch in Hanoi and Ralph Jennings in Taipei; Editing by Ron Popeski)