By David Lague
HONG KONG, Sept 21 (Reuters) - The dispute between China and Japan over a desolate jumble of rocky islets in the East China Sea has taken a familiar turn with Beijing deploying a fleet of paramilitary patrol ships while similar Japanese vessels steam out in response.
As in earlier disputes over rocks and shoals in the South China Sea, Beijing is relying on these vessels rather than more menacing warships to assert its sovereignty over the disputed islands known as Diaoyu in China and Senkaku in Japan.
For both sides, the presence of lightly armed paramilitary ships reduces the risk of conflict, maritime experts say, while they retain the option of deploying more firepower if the dispute intensifies.
However, unlike China's recent sparring with the Philippines over Scarborough Shoal, this flare-up pits East Asia's two maritime powers against each other in a confrontation loaded with military risk.
If a clash erupted, experts warn it could be difficult to contain to the disputed area and would likely draw in the United States, Japan's security alliance partner, into hostilities with China.
The U.S. assistant secretary of state for East Asia, Kurt Campbell, said on Thursday the disputed islands were "clearly" covered by a 1960 treaty obliging the United States to come to Japan's aid if attacked.
"I actually don't think the two sides intend to fight a war over the islands this time," said Sun Yun, an expert on Chinese security policy at the Washington-based Stimson Centre.
"But, I do think it is more dangerous because the current round of tension is more emotionally charged than the earlier stand-offs in the South China Sea."
Politics may well keep the row simmering in the months ahead with a Japanese election expected by year's end and China preparing a leadership transition.
STEP INTO UNKNOWN
While China's maritime rise has captured global attention, Japan has also been quietly and unobtrusively building a powerful navy boasting some of the most advanced military technologies afloat.
If tensions over the disputed islands led to military conflict, it is not clear that China's navy could overpower Japanese forces as easily as it might expect to prevail against militarily weaker rivals in the South China Sea.
For both militaries, a naval clash would be a step into the unknown.
Japan's pacifist Constitution has insulated its navy from combat since it was shattered in the final stages of World War Two.
Modern China's navy is still in its infancy and also has no fighting experience.
In its three-decade military build-up, Beijing has transformed what was a rusting, obsolete, coastal defence force into a blue water navy that is increasingly capable of mounting deployments and complex operations far from the Chinese mainland.
In raw numbers, China is now the world's second-ranked naval power behind the United States with a fleet including about 80 major warships, 53 submarines, 50 landing ships and 86 missile patrol boats.
With a combination of Russian and homegrown hardware, it has deployed multi-ship fleets through the Japanese island chain and out into the Pacific ocean for exercises and training. Its ships have taken part in international anti-piracy operations in the Indian ocean. It has a fleet of advanced conventional submarines.
The most powerful Chinese warships and submarines are armed with deadly, Russian-made supersonic anti-ship missiles. However, the Chinese navy lacks operational training and experience, naval experts say.
BIGGER THAN BRITAIN'S
Japan's Maritime Self Defence Force is clearly smaller with about 48 major warships and 16 submarines but it remains a formidable force compared with other traditional naval powers.
It has twice as many surface warships as Britain's Royal Navy and twice as many submarines as the French navy.
Some of its key surface warships are equipped with the advanced U.S. Aegis combat system that combines computers, radars and information from other ships, satellites or aircraft to track multiple targets and guide attacking missiles.
Japan's conventional submarines are also regarded as some of the most advanced and stealthiest in the world.
Naval experts say the Japanese navy is also a highly trained professional force that has exercised for decades in its major roles of sea lane protection and anti-submarine warfare. It has also trained regularly with U.S. forces.
If a clash took place in the area of the disputed islands between the Japanese island of Okinawa and Taiwan, both sides could deploy land-based strike aircraft to support their forces.
However, security experts say it is highly unlikely that any fighting would be restricted to naval and air units in the disputed area.
Beijing might tempted to use its huge arsenal of 1,200 ballistic missiles aimed at Taiwan to attack Japanese forces and bases.
If China was the aggressor, they say the United States would almost certainly support Japan.
"I don't think the U.S. could stand aside," said Ross Babbage, a security analyst and former senior Australian defence official. "There would be a huge international crisis and I'm not expecting that."
"And, I don't think either side really wants it."
However, there is always the danger of miscalculation and accident with big fleets of paramilitary patrol vessels on station and civilian protestors from both sides making landings on the uninhabited islands.
This risk is likely to remain, even if the current round of tension eases, maritime security analysts say.
The arrival of China as a naval power means Beijing now has the means to challenge Japan's control over disputed maritime territory in the East China Sea and the oil and gas thought to lie beneath.