Why are citizens from Japan and China fighting over East China Sea islands?

OSAKA, Japan — So much for the dog days of summer providing momentary respite for senior politicians. For leaders in China, Japan and South Korea, festering territorial disputes threaten to spiral into a full-blown crisis.

That much was apparent this weekend, when 10 Japanese nationalists landed on a group of islands at the center of a dispute with China, four days after pro-China activists from Hong Kong elicited a furious response from Tokyo by landing on the same tiny outcrop.

That earlier landing on the Senkaku islands, known as the Diaoyu in China, presented Japan with a second diplomatic headache, coming less than a week after the South Korean president Lee Myung-bak, made a high profile visit to Takeshima — a disputed island chain known as Dokdo in South Korea.

Japan briskly deported the activists in an attempt to avoid a diplomatic showdown of the kind that damaged relations in 2010. That spat was sparked by a clash between a Chinese fishing trawler and two Japan coast guard vessels near the Senkakus. It ended a fortnight later with the release of the trawler's skipper, but only after damage was inflicted on trade and people-to-people exchanges.

Why have the Takeshima and Senkaku disputes come to a head now?

It is no accident that the latest provocative gestures came in as countries in the region were marking Japan's defeat in the Pacific War.

Japan's territorial claims are inextricably linked with its military adventures in parts of the China and on the Korean peninsula in the first half of the last century.

South Korea's decision to stage a coast guard battalion on Takeshima in 1952 was its way of "taking back" territory it had lost shortly before Japan began its 1910-1945 colonial rule of the Korean peninsula.

More from GlobalPost: Senkaku Islands spark territory dispute between China and Japan

The San Francisco peace treaty made no reference to the islands' fate when it was signed in 1952, the same year the government in Seoul dispatched coast guards and, to lend legitimacy to its claims, a fisherman and his wife who remain Takeshima's only civilian residents.

According to China, the Senkakus were Chinese until they were annexed by Tokyo after the 1894-95 Sino-Japanese War. In Beijing, as in Seoul, Japan's defiant retention of these rocky outcrops is simply a hangover from its militarist past.

History is a powerful catalyst in rallying public sentiment, but it is not the only factor at play. Both sets of islands are surrounded by potentially vast oil and natural gas deposits that could go some way towards satisfying the region's insatiable appetite for new energy sources.

But any potential economic benefits are less important in the short-term than the islands' role as a rallying point for the region's increasingly vocal nationalists.

In this video, Chinese nationalists overturn Japanese cars and shout, "Return our Diaoyu Islands."

The Senkaku dispute only started to approach boiling point after Tokyo's rightwing governor, and unashamed China baiter, Shintaro Ishihara, announced plans in April to buy three of the five islands from their private Japanese owners. Within months, Ishihara's project had attracted more than $18 million in donations.

Under pressure to remove the sting from Ishihara's provocation, the prime minister, Yoshihiko Noda, unveiled a rival bid by the national government that, if successful, will effectively nationalize the islands.

Ishihara has an unlikely bedfellow in Lee Myung Bak. Lee — faced with myriad problems at home, and determined to secure a positive legacy before he is replaced as president in December — has transformed himself from a relatively Japan-friendly leader into one of its most forthright critics.

He followed up his surprise visit to Takeshima, made under the guise of promoting its ecological riches, by demanding that Japan's emperor apologize for Japan's brutal occupation of the Korean peninsula, should he ever wish to pay a visit.

Lee also reopened the controversy over Japan's sexual enslavement of Korean women before and during the war, demanding that it issue an apology and compensate the "comfort women" to demonstrate its sense of "responsibility."

His rhetoric was reflected in a particularly intemperate editorial in the Korea Herald: Japan, it said, had "never really repented, at least in the eyes of its victims for the wrongdoings and focused only on economic revival under the patronage of its former conqueror, the United States.

"It's no surprise that Japan, led by rightist politicians, the most vocal group in Japanese politics, has turned around to deny and even justify its wartime atrocities. "

The causes of the squabbles over tiny, isolated dots of land are clear, if complicated. What is less certain is how far the three sides involved will allow them to escalate.

A military confrontation is unlikely, but there are signs that the uncomfortable diplomatic truce that has been in place for decades could be about to break.

Japan has called for the Takeshima row to go before the International Court of Justice, although the court won't adjudicate unless South Korea agrees to cooperate. Seoul's line has been consistent and unequivocal: why discuss sovereignty when the islands, occupied by its own citizens, are demonstrably Korean? 

In China, thousands of people joined anti-Japanese demonstrations in several cities over the weekend – the kind of street protest Beijing is happy to tolerate as it prepares for a once-in-a-decade change in the Communist party's hierarchy.

In Japan, too, the appetite for action is growing. The conservative Yomiuri Shimbun called on the coast guard to "beef up" its equipment and personnel, and described the recent landing by activists from Hong Kong "an act of defiance against Japanese sovereignty."

And in a poll conducted last week, the Japanese Nihon Keizai Shimbun found that 90 percent of respondents found Lee's visit to Takeshima "intolerable," while a third called for economic retaliation, possibly to include the cancellation of a currency-swap deal that many see as more advantageous to South Korea.

An escalation in tensions between Japan and South Korea would be unsightly, but would probably do little to derail the close economic and cultural ties that see 5 million citizens flying between the two countries every year.

More worrying is the possibility of a trade spat between China and Japan, Asia's two biggest economies. That said, they have pulled back from comprehensive sanctions and naval standoffs before, and there is no reason to believe this time will be any different, even if the stakes are slightly higher.

But with activists from both countries reportedly planning more visits to the Senkakus in the coming weeks, there is still scope for the unexpected to happen before the summer is out.