Tokyo's seeming fixation with squabbles over the outposts of its former empire are symptomatic of a foreign policy drift as Japan struggles to find its place in the 21st century, analysts say.

In a little over a month, three long-running territorial disputes have flared up.

Russian Prime Minister Dmitry Medvedev inflicted the first wound in early July with a visit to the Kurils, off the coast of Hokkaido, seized by the Soviet Union in the last days of World War II.

"I do not care," Medvedev told reporters when asked what he thought about Tokyo's "extreme regret" over his trip to what Japan calls the Northern Territories.

South Korean President Lee Myung-Bak sent relations plunging when he flew to Dokdo, islets in the Sea of Japan (East Sea) that Tokyo calls Takeshima.

And last week Tokyo deported 14 pro-Beijing activists who had sailed to a chain of islands known as Senkaku in Japan and Diaoyu in China, the most bitter of its territorial scraps.

Japanese nationalists hit back with their own landing on Sunday.

Each incident was deeply felt in Tokyo, where a directionless government, destabilised by domestic rows over nuclear power and consumption tax, is stumbling towards a seemingly inevitable election in the autumn.

All the disputed islands harbour valuable resources -- petrochemical, mineral or fishery -- but they are also strategically valuable in a part of the world keenly aware of the rising power of China.

"Senkaku is a window on the continent," said Hideshi Takesada, a Japanese professor of Asian Studies at Yonsei University in South Korea.

"If Japan lost Senkaku, it would lose a significant portion of its frontline defence.

"Moreover, a weak-kneed response will lead to similar results in other fields. China, for instance, may gain the upper hand in patent fights and other bilateral and regional disputes."

Issues linked to Japan's early 20th century expansionism, when it conquered large swathes of east Asia, often brutally, arouse particularly strong feelings in the region, said Takashi Terada of Doshisha University in Kyoto.

"Europe has more or less sorted out the legacy of the Cold War, but it is still visible in Asia. A lot of territorial disputes have remained unresolved," he said.

Indeed, Japan has never signed a peace treaty with Russia to formally end World War II because of the disagreement over the Kurils.

But Japan's inability to head off these fights or to put an end to them when they surface is, says Terada, a function of its listless domestic politics, which has left the country exposed on the global stage.

He says the inexperience of the Democratic Party of Japan, which came to power in 2009 after five decades of almost unbroken rule by the Liberal Democratic Party, is a problem, with key figures enjoying few of the personal cross-border links their predecessors developed over long periods in office.

The frequent changes at the top of government -- Yoshihiko Noda is Japan's sixth premier in as many years -- are destabilising, and give the impression Japan cannot hit back, he said.

China's economic rise and Japan's stagnation have also altered the regional balance.

"Neighbouring countries used to need Japan's financial and technological cooperation," he said. "In exchange for that, they would tone down their diplomatic stance."

The deterioration of Japan's relationship with the United States, with recent Tokyo administrations appearing lukewarm on ties with the country's most important security ally, have also given neighbours a way in.

"While Japan was firmly protected under its security alliance with the United States, it did not have to be so serious about territorial issues.

"But Japan's recent unfavourable relations with the United States are allowing China and South Korea to gain the upper hand."

But Tetsuro Kato of Tokyo's Hitotsubashi University warned Tokyo cannot simply go scurrying back to Washington.

This is partly because the US has no interest in getting its hands dirty in territorial battles where whatever it does risks damaging its own interests, he said, but also because the balance of world power has shifted.

"With the growth of China, Japan can no longer depend only on the United States," he said.

And with demands at home for something to be done, politicians could find themselves increasingly bounced into making the kind of statements Noda made last month when he said Japan could send in the military to defend the Senkakus.

Thomas Berger, associate professor of International Relations at Boston University, said in the short term there would be no actual military conflict.

"However, the growing embitterment of public sentiment in the region over territorial disputes is a source of real concern," he said.

"The possibility of a clash cannot be ruled out, and a regional arms race is already well under way."