SAPPORO, Japan — Takashi Uemura was 33 when he wrote the article that would make his career. Then an investigative reporter for The Asahi Shimbun, Japan’s second-largest newspaper, he examined whether the Imperial Army had forced women to work in military brothels during World War II. His report, under the headline “Remembering Still Brings Tears,” was one of the first to tell the story of a former “comfort woman” from Korea.

Fast-forward a quarter century, and that article has made Mr. Uemura, now 56 and retired from journalism, a target of Japan’s political right. Tabloids brand him a traitor for disseminating “Korean lies” that they say were part of a smear campaign aimed at settling old scores with Japan. Threats of violence, Mr. Uemura says, have cost him one university teaching job and could soon rob him of a second. Ultranationalists have even gone after his children, posting Internet messages urging people to drive his teenage daughter to suicide.

The threats are part of a broad, vitriolic assault by the right-wing news media and politicians here on The Asahi, which has long been the newspaper that Japanese conservatives love to hate. The battle is also the most recent salvo in a long-raging dispute over Japan’s culpability for its wartime behavior that has flared under Prime Minister Shinzo Abe’s right-leaning government.

This latest campaign, however, has gone beyond anything postwar Japan has seen before, with nationalist politicians, including Mr. Abe himself, unleashing a torrent of abuse that has cowed one of the last strongholds of progressive political influence in Japan. It has also emboldened revisionists calling for a reconsideration of the government’s 1993 apology for the wartime coercion of women into prostitution.

“They are using intimidation as a way to deny history,” said Mr. Uemura, who spoke with a pleading urgency and came to an interview in this northern city with stacks of papers to defend himself. “They want to bully us into silence.”

“The War on The Asahi,” as commentators have called it, began in August when the newspaper bowed to public criticism and retracted at least a dozen articles published in the 1980s and early ’90s. Those articles cited a former soldier, Seiji Yoshida, who claimed to have helped abduct Korean women for the military brothels. Mr. Yoshida was discredited two decades ago, but the Japanese right pounced on The Asahi’s gesture and called for a boycott to drive the 135-year-old newspaper out of business.

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