Japanese Prime Minister Junichiro Koizumi prayed at the Yasukuni war shrine Tuesday to mark Tokyo's World War II surrender, defying strident protests by China and South Korea but cheering his conservative followers.

It was Koizumi's sixth visit to the shrine since taking office in 2001, but his first on the highly symbolic Aug. 15 anniversary of Japan's 1945 defeat. He is the first prime minister to make such a visit since Yasuhiro Nakasone in 1985.

The shine visits have been a lightening rod for critics who accuse Japan of failing to properly atone for its military invasions in the 1930s and 40s. The shrine honors convicted war criminals among Japan's 2.5 million war dead.

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The move was certain to trigger emotional protests from China and South Korea, who are refusing to hold summits with Koizumi because of the visits. Koizumi is to step down as prime minister in September.

Japanese supporters, however, say the visits are an internal affair.

Opponents who consider the shrine a glorification of Japan's past militarism have been mounting protests in recent days to urge Koizumi to stay away and call on Tokyo to more fully atone for its pre-1945 aggression.

Yasukuni honors Japan's 2.5 million war dead, including war criminals executed after World War II such as warime Prime Minister Hideki Tojo. The shrine played a high-profile role in promoting wartime nationalism, and even today it hosts a museum that seeks to justify Japan's invasions of its neighbors.

The Koizumi visits have triggered fierce protests in China and South Korea, two countries that suffered deeply under Japanese militarism.

"The government has to make the strongest diplomatic reaction if the prime minister goes ahead with paying homage to the Yasukuni Shrine," Kim Han-gill, floor leader of South Korea's ruling Uri Party said Monday, according to his party.

In a rare show of bipartisan unity, the country's main opposition Grand National Party also urged Koizumi not to visit the shrine, calling the trip "a second invasion."

In Japan, the visits have split opinion down the middle.

Supporters say Koizumi has the right to honor those who died for the country, while China and South Korea have no business interfering in Japan's internal affairs.

Opponents, however, have urged Koizumi not to antagonize Japan's neighbors. Some have filed lawsuits against the visits, saying they violate the constitutional division of religion and state. One such suit was recently rejected by the Supreme Court.