In the clearest signal yet of U.S. unhappiness with the rightward tilt of Japan’s political leadership — and by extension, Prime Minister Shinzo Abe — the U.S. embassy in Tokyo has strongly condemned charges by a top official at Japan’s national public broadcaster that Americans fabricated war crimes against Japanese leaders during World War II in order to cover up American atrocities.

“These suggestions are preposterous. We hope that people in positions of responsibility in Japan and elsewhere would seek to avoid comments that inflame tensions in the region,” an embassy spokesman told TIME early on Friday.

The charges were made this week by Naoki Hyakuta, a nationalist writer and close friend of Abe, who was recently appointed to the board of governors of the Japan Broadcasting Corp., commonly known as NHK.

In campaign speeches on behalf of a far-right candidate for the governorship of Tokyo, Hyakuta claimed that the infamous Nanjing Massacre in 1937 never occurred, and that Americans staged the postwar trials of Japanese leaders to cover up U.S. war crimes. He said those crimes included the atomic bombings of Hiroshima and Nagasaki and the mass firebombings of Tokyo.

The staunchly conservative Abe himself caused diplomatic outrage in December, when he paid his respects at Tokyo’s Yasukuni Shrine — a memorial to the Japanese war dead including 14 high-ranking war criminals. Beijing, Seoul and Washington strongly condemned the visit. Now supporters of Abe who have been appointed to NHK’s top decisionmaking body are fueling tensions by making revisionist or inflammatory statements.

Last week, the new NHK chairman Katsuto Momii provoked outrage both at home and abroad when he said all of the countries involved in World War II maintained “comfort women” — a euphemism for the system of forced prostitution employed by the Japanese military during the war years.

That charge prompted a frosty denial from the U.S. embassy in Tokyo that American forces had engaged in any such activity.

Along with Hyakuta’s charges, it was reported this week that another NHK board member had published an essay praising the leader of a nationalist group who committed ritual suicide in the offices of a major newspaper in October 1993 to protest negative news coverage.

Board member Michiko Hasegawa wrote that because the activist recited a brief prayer to the Emperor before shooting himself in the abdomen, “His Majesty the Emperor has again become a living god.” Hasegawa is a professor emeritus of Japanese cultural studies in Tokyo.

Japan’s Emperors were once worshipped as living gods, but are designated under the current constitution as “the symbol of the state and of the unity of the people.” As such, they have no governing authority or official religious function.

Hasegawa, who also has close ties to Abe, published the essay in connection with a ceremony marking the 20th anniversary of the activist’s death.

The appointment of such staunch nationalists to NHK’s board is part of a concerted campaign by the Abe administration to recast Japan as the true victim of World War II and put a more benign face on the country’s often brutal colonial practices, says Jeff Kingston, professor of Asian studies at Temple University’s Tokyo campus.

“These are Abe’s cronies, they agree with his revisionist views, and now he’s putting them in positions of power and influence,” says Kingston. “What they don’t realize is that the right-wing revisionists are not convincing many people in Japan, and they are not convincing people outside Japan. What they are doing is creating a huge diplomatic problem.”

Japan is locked in increasingly tense disputes with neighboring China and South Korea over territorial and historical issues. A spokesman for China’s Foreign Ministry denounced Hyakuta’s statements on the Nanjing Massacre as “a barefaced challenge to international justice and human conscience” and called on Japan to “face up” to its history.

China says 300,000 Chinese soldiers and civilians died in Nanjing during a weeks-long rampage by Japanese troops. Although some mainstream historians put the number of casualties lower, few — if any — deny the incident occurred.

Critics say the Abe appointees threaten the editorial integrity of Japan’s largest broadcaster.

“Just the knowledge of the character of the governors leads producers and journalists working for NHK to engage in self-censorship,” says Michael Cucek, a Tokyo-based research associate at MIT’s Center for International Studies.

Indeed, NHK did not report chairman Momii’s controversial statements on comfort women until he was grilled by opposition members during a Diet session three days afterward. Nor had news of the debate over Hyakuta’s and Hasegawa’s statements appeared on the NHK news website as of early Friday — despite more than 7,200 messages, mostly negative, phoned in or emailed to NHK’s headquarters.

Members of the opposition have called for the appointees to be replaced, but an Abe spokesman said all had been speaking in their capacities as private citizens and had not violated government policy.

NHK is Japan’s largest television network, funded largely by viewer license fees. It produces round-the-clock entertainment and public-interest programming and operates news bureaus around the world.

The 12 members of NHK’s board serve three-year terms. They are appointed by the Prime Minister with approval of the Diet and exercise authority over NHK’s annual budget and top executives.

Hyakuta is the author of several best-selling books, including The Eternal Zero. Abe and his wife attended a screening of the film version of the book over the New Year holiday. The movie ends with the hero, a pacifist fighter pilot turned Kamikaze, flying his airplane into an American aircraft carrier.

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