A Japan Coast Guard vessel, right, sprays water against Taiwanese fishing boats in the East China Sea near the islands known as Senkaku in Japanese and Diaoyu in Chinese, on Sept. 25, 2012. (Yomiuri Shimbun/AFP/Getty Images)

These are tense times in Asia’s waters. In just the past month, Vietnam accused a Chinese vessel of ramming one of its fishing boats, damaging the hull. The Philippines protested that a Chinese warship and two surveillance vessels had intruded into its territory. Farther north, Chinese boats darted around Japanese-controlled islands for five straight days, staking claim to an area Japan considers its own.

Over the last few years, China’s maritime conflict with its neighbors has taken the shape of such minor but contained skirmishes: standoffs between ships, boat collisions, arrests of fishermen, cat-and-mouse games between aircraft over disputed territory. But the quickening pace of these encounters points to what experts see as China’s fundamental strategy — using the seas as the stage on which to prove itself as Asia’s dominant power.

China has set off on a bold mission to control the waters around it, sparking regional tensions that could last decades, policymakers and security experts say. Amid recent signals that Beijing’s new leadership views maritime power as a fundamental national goal and is willing to spar over a massive area of water that swings from Southeast Asia to Japan and reaches into the Pacific Ocean, those experts increasingly warn that China’s rise will be contentious, not peaceful.

China’s maritime disputes with its neighbors had been expected to be discussed during meetings Friday and Saturday between President Obama and his Chinese counterpart, Xi Jinping, in California, part of a broader security conversation that will also include the expanded U.S. military deployment to the region.

While the latest incidents on the seas haven’t provoked violence, they have added to an already risky environment in which countries are modernizing their militaries, have little appetite for backing down and are raising the odds of a bloody miscalculation that could draw in the United States, which has defense treaties with Japan and the Philippines.

Island disputes in Asia

The disputes involve more than half a dozen countries, with those on China’s periphery seeing Beijing as the provocateur, recently pressing disputes that had long been dormant.

China’s ‘strategic window’

A recent Pentagon report to Congress said that Chinese leaders view the first two decades of this century as a “strategic window of opportunity” in which to expand their nation’s power, measured not only by economic benchmarks but also by their ability to defend territorial claims and “win potential regional conflicts.”

Even if China avoids conflicts, analysts say, its very preparation for them has pushed other militaries to respond, most recently with the Philippines purchasing new warships. Japan’s ruling party is even considering changes to its pacifist constitution.

During her visit to the United States in May, South Korean President Park Geun-hye described the situation as a regional paradox — one in which Asian nations are closely linked economically but increasingly at odds.

“How we manage this paradox — this will determine the shape of a new order in Asia,” she said.

China’s expansive strategy comes as the United States pivots its military toward Asia in an effort to maintain a balance of power in a region long known for relative peace. A “big part” of that shift “has been to work to shape the region and to influence China’s behavior and China’s emergence as a major actor in a positive way,” a senior Obama administration official said this week, speaking on the condition of anonymity to discuss the leaders’ summit in advance.

Beijing is driven not only by the possibility of offshore energy development and fishing resources but also by the basic prestige of expansion — of wresting control of areas with deep histories of dispute. Part of China’s motivation is also nationalistic, particularly when it comes to a dispute over a group of rocks and islets controlled by rival Japan, a former invader and occupier.

Just five years ago, it was almost unheard of for China to send patrol vessels to the islets. But in the five months after Japan last year purchased several of the islets from a private owner — previously, it had rented them — Chinese vessels entered Japanese territorial water 25 times, according to Japan’s Foreign Ministry.

Japanese leaders say China’s ruling Communist Party uses disputes to bolster its legitimacy at a time of slowing economic growth and domestic frustration. But nationalist sentiment could also complicate a crisis, limiting the options for Chinese leaders if they want to de-escalate. Chinese aggression could also backfire if other countries in the region cooperate with one another or modernize their own militaries in response.

“To some degree, being aggressive on these issues might hurt the reputation of China,” said Zhou Weihong, a Japan specialist at the Beijing Foreign Studies University. “It’s normal that you will be misunderstood when you are growing stronger and when you [make] demands for your own interests which you never did in the past. . . . Smaller countries that lose out in disputes will regard the stronger and bigger country as a bully.”

The ‘nine-dash line’

China stakes out maritime territory with a mix of strategies, using legal claims, historical arguments and a built-up military force.

China’s most notable territorial conflicts involve Japan, the Philippines and Vietnam, but its claims also overlap with the territory of Brunei, Taiwan and several other nations. The countries most at odds with China are left with an unappetizing choice: They can either cede ground or lock horns with a country whose defense budget has grown 30-fold over the past 25 years.

China considers nearly the entire South China Sea its own, illustrating its claim with a legally dubious “nine-dash line” — quite literally, nine intermittent dashes that encircle the sea. Late last year, China also unveiled new baseline claims around the islets disputed with Japan in the East China Sea. Xi, China’s new leader, has vowed to never bargain over key national interests, including territorial claims.

Chinese leaders sometimes say that other nations are instigating the fight by increasing their own military spending, by beefing up their coast guards or by reasserting claims on disputed territory — as Japan did last September, when its central government purchased disputed islets.

But others say that China uses those perceived affronts as an excuse to pounce. After such provocations, China tends to take “strong countermeasures to change the status quo in its favour,” the International Crisis Group wrote in a recent report.

Five islets and three rocks

Those tactics can be seen most clearly in the waters surrounding the five islets and three rocks known to Japanese as the Senkaku Islands and to Chinese as the Diaoyu Islands.

Just one day after Japan purchased several of the islets, China released a set of latitude and longitude coordinates marking what it says is its territory in the area. Those markings, under Chinese law, stated the islets belong to Beijing.

“China’s intention to topple the status quo concerning Japan’s valid control by coercion is clear,” the Japanese Foreign Ministry said months later, as Chinese boats were sighted almost daily around the islets.

Japanese officials say the purchase was in part driven by years of Chinese military build-up, with Chinese vessels advancing into Japanese territory every year since 2008, sometimes to conduct war drills in the Pacific. In one 2008 case, four Chinese vessels circled around Japan, sliding through a northern island chain near Russia and returning through a southern island chain near Okinawa.

In the East China Sea, a Chinese military vessel in January briefly locked its weapons-targeting radar on a Japanese warship, top Japanese officials said. Japanese Prime Minister Shinzo Abe called on China to “strictly” refrain from further “dangerous acts that would escalate the situation.”

The opposite has happened. In April, China’s Foreign Ministry defined the islands as a “core interest,” a loosely defined term that Beijing uses for its top national priorities, ones worth going to war over.

“I think it’s inevitable that skirmishes and minor conflicts happen,” said Narushige Michishita, a security specialist at the Tokyo-based National Graduate Institute for Policy Studies. “The question then is how to not let it escalate, and that’s where dialogue, planning and top-level communication become very important.”

Yuki Oda in Tokyo and Liu Liu in Beijing contributed to this report.