Q+A - Why does Japan's war shrine make China so angry?

BEIJING (Reuters) - China voiced anger on Thursday with Japanese Prime Minister Taro Aso for sending an offering of a potted tree to the Yasukuni shrine for war dead, long a source of discord between the two Asian powers.

Following are questions and answers on why the shrine still stirs such passion in China.

WHAT IS YASUKUNI SHRINE AND WHY IS IT CONTROVERSIAL?

Established in 1869 and funded by the Japanese government until 1945, Yasukuni is dedicated to Japan's 2.5 million war dead, including about 1,000 convicted war criminals.

Among those honoured are 14 World War Two leaders convicted by an Allied tribunal as "Class A" war criminals, including wartime Prime Minister Hideki Tojo.

Many Chinese and Koreans resent the honours accorded by the shrine to the war criminals. Koreans still chafe over Japanese rule from 1910 to 1945, while China has bitter memories of Japan's invasion and brutal occupation of parts of the country from 1931 to 1945.

A war museum attached to the shrine has also come under fire for glorifying Japan's invasion of its Asian neighbours.

WHY DOES DISCORD PERSIST SO LONG AFTER THE WAR?

Visits by Japanese leaders to the shrine deeply upset Japan's neighbours, who see it as a symbol of Japan's past militarism, while Japanese conservatives believe that their leaders should be able to pay their respects to those who died in the war.

Sino-Japanese ties chilled during Junichiro Koizumi's 2001-2006 term as prime minister, in part due to his annual pilgrimages to the shrine.

Chinese students marched in several cities in the spring of 2005, partly to protest against the shrine visits.

Relations between the Asian rivals and trade partners warmed after Koizumi's successor, Shinzo Abe, refrained from visits to the shrine and both governments put priority on improving ties.

China responded with only a moderate rebuke when Abe made a similar offering of a potted plant in 2007.

WHY DID ASO SEND AN OFFERING NOW?

Aso has not visited the shrine while in office out of consideration for bilateral ties, but with a tough general election looming in a few months the outspoken nationalist premier may have wanted to cultivate his conservative base.

Aso may also have calculated that his decision to refrain from paying his respects in person while offering a $500 "masakaki," or potted tree, for which he paid for with private funds was a compromise that Beijing could accept.

WHY IS CHINA SO ANGRY?

The offering, which coincided with a visit to Yasukuni by dozens of Japanese lawmakers during a spring festival this week, is considered by China as honouring convicted war criminals.

Springtime ritual offerings at the shrine are traditional in Japan, but this offering especially rankles coming just before next week's China-Japan summit.

Beijing's response may also have been an effort to placate outraged public opinion when the economy is going through a rough patch because of fallout from the global financial crisis.

WHAT IS THE RISK OF THE DISPUTE ESCALATING?

Analysts say the dispute will cast a cloud over Aso's April 29-30 visit to China, but probably not escalate into a rerun of the 2001-2006 bilateral freeze.

China is Japan's No.1 partner in terms of total trade and its No. 2 destination for exports after the United States, and Japan needs the Chinese market for its goods to help recover from its worst recession in 60 years.

China, for its part, needs Japanese investment.

Leaders in both countries are likely to want to keep the dispute from boiling over, but public opinion is a wild card. Japanese voters who may not care deeply about Yasukuni have in the past been angered by perceived Chinese interference over the issue.

The Chinese public reaction to Aso's offering has reached nowhere near the pitch of past years. But Chinese-language internet sites have carried bitter denunciations of Aso, and the government may fear renewed protests ahead of the sensitive anniversary of the armed crackdown on pro-democracy demonstrations in 1989.

(Reporting by Lucy Hornby and Chris Buckley in Beijing and Linda Sieg in Tokyo; Editing by Alex Richardson)