China takes to the streets after falling out with the neighbours

A collision between a fishing boat and the coast guard does not, on the face of it, sound like an internationally significant incident. Nor does the death of a panda. But when the parties involved are China and Japan, the stakes are considerably higher.

Relations between the two countries are never easy. But as police prepare for Chinese demonstrators taking to the streets today to mark the 79th anniversary of the Japanese invasion, tensions are particularly high. Protests are not a regular feature of the anniversary, but recent diplomatic incidents have brought one of the most crucial relationships in the region into as sharp a focus as ever.

The spat was sparked last week when Japanese coast guards chased a Chinese trawler which had entered waters near a group of islands controlled by Japan but claimed by China, called Diaoyu in Chinese and Senkaku in Japanese. They are located some 190 kilometres east of Taiwan.

The Japanese arrested the captain after the Chinese vessel collided with two Japanese patrol boats. The captain could face prosecution, although the trawler and its 14-member crew have since returned to China.

And as if that incident were not enough, a difficulty over an endangered species has emphasised still further how tricky relations remain. That episode began when a Chinese male giant panda called Kou Kou, or Xing Xing in Chinese, died in a Japanese zoo after it was sedated so that it could donate semen in an artificial insemination programme. The giant panda is China's national symbol, and the death of one is considered a big issue.

The 14-year-old Kou Kou died of a heart attack after failing to recover from an anaesthetic at the Oji zoo in Kobe. Zoo officials said they are investigating its death, and a team of Chinese officials has joined them. The zoo faces a penalty of up to £300,000.

Neither of these incidents would count for much in isolation. But even though economic relations between the two neighbours are good, the Chinese still bitterly resent the brutal occupation of China by the Imperial Army, which began with the Japanese invasion of Manchuria in 1931.

Many Chinese insist Tokyo has never shown adequate contrition for atrocities carried out during the occupation, including the "Rape of Nanking", which began when Japanese troops invaded China's wartime capital on 13 December 1937. Chinese historians claim that over a six-week period more than 300,000 people were killed, although some Japanese historians insist the number was much lower.

Huang Dahui, of Renmin University's International Relations department, said the current row is all about "face", but has a major historical background. Mr Huang points to the period five years ago when relations hit rock-bottom over then-Prime Minister Junichiro Koizumi's visits to the Yasukuni Shrine, where Japanese war criminals are among the war dead commemorated – a gesture that was likely to inflame tensions.

Today's anniversary, he said, is likewise bound to be difficult. "September 18 is a very important day for both governments to think about their relations and reflect on the lessons of war. What I cannot understand is how on this most sensitive of days, the Japanese government still chose to deal with the issue in this way, which is guaranteed to pull the nationalism trigger in China," Mr Huang said. He believes the power structure is changing because of China's growing economic influence, prompting Japan to behave in "a less proper way".

If protests do break out today – though the organisers insist they have no such intention – it will echo a particularly difficult period in 2004, when violent anti-Japanese riots over the publication of a history textbook in Japan, which the Chinese said minimised atrocities carried out during the occupation of China, further inflamed tensions. Japanese businesses and the country's embassy were attacked, and Japanese made products were destroyed in the incidents, which marked a low-point since relations normalised in 1972.

The latest crisis has not reached such worrying heights. But as long as a panda and a fishing boat can bring people to the streets, it is hard to see the two countries behaving in as neighbourly a way as their mutual economic interests might suggest they should.