Protesters in front of the Japanese embassy in Beijing

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, reports Reuters.

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.

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.