Prime Minister Shinzo Abe this week will be the first Japanese leader to visit the USS Arizona Memorial and pay tribute to the victims of Pearl Harbor, a gesture he hopes will help heal the wounds from the attack 75 years ago and strengthen the Japan-U.S. alliance.

Whether Abe’s speech in Honolulu will be a political success remains to be seen. But the visit is unlikely to end the historical debate over the Dec. 7, 1941, attack, let alone ease the die-hard conspiracy theories that continue to stir interest on both sides of the Pacific.

Key among them is the belief that then-U.S. President Franklin D. Roosevelt knew of Japan’s plans to attack, because the U.S. had cracked Japan’s naval codes yet did nothing to prevent it or prepare for it.

This claim was laid out in the 2000 book “Day of Deceit” by Robert Stinnett.

Stinnett, a U.S. Navy veteran, argues that Roosevelt let Japan start a war with the United States because he wanted to enter World War II in order to help Britain, which was on the ropes at the hands of Nazi Germany.

Stinnett’s theory is another variation of a long circulated suspicion among many Americans that Roosevelt let Japan attack Pearl Harbor so the U.S. could enter the war through the “back door.”

This theory gained traction when Pulitzer Prize-winning author and historian John Toland published the 1982 book “Infamy: Pearl Harbor and its Aftermath.”

Mainstream historians in Japan assume Roosevelt wanted Japan to start war with the U.S. But there is no clear evidence showing Roosevelt knew specifically that Japan was targeting Pearl Harbor, and on the contrary there are indications that he expected Japan to strike somewhere in Southeast Asia, the historians say.

“It’d be fascinating if such a conspiracy theory is true. So I have kept looking for evidence but I have found none,” said Shinji Sudo, a professor emeritus at Kyoto Sangyo University and a leading Japanese historian on Pearl Harbor attack studies.

“It’s a pity but the conspiracy theory won’t hold,” said Sudo, who has been investigating Pearl Harbor conspiracy theories for years.

In his book, Stinnett claimed the U.S. had broken the Japanese naval code called JN-25b before Pearl Harbor and thus Roosevelt must have known of Japan’s plan in advance.

Mainstream historians, however, say official records only show that U.S. intelligence teams were able to decode JN-25b after March 1942, months after the devastating surprise attack.

Stinnett offered no records of Japanese naval cables deciphered before Pearl Harbor, according to retired Vice Adm. Naotoshi Sakonjo, a military historian and former communications expert at the Maritime Self-Defense Force.

Stinnett included photocopies of two naval cables in his book as examples of deciphered communications. One of them is with a date record of “Navy Trans 4/24/46,” meaning, according to Sakonjo, that it was deciphered and translated into English on April 24, 1946. The serial number of the other is SRN115376, which means the cable is from a group of those deciphered after April 1942, Sakonjo said.

“I read through the book and wondered how it came to be published. Then I was dumbfounded when the translated (Japanese) version was published because many famous scholars and critics praised the book to the skies,” Sakonjo wrote in an article in the January 2012 issue of Rekishi Tokuhon, a history magazine.

Sakonjo and other three Japanese experts later published a book in 2001 to rebuff the conspiracy theories involving Roosevelt and Pearl Harbor.

But now many Japanese apparently believe Stinnett’s theory. Japanese versions of the book are still being sold in Japan.

“People tend to just believe what they want to believe. Conspiracy theories will survive as long as such tendencies exist,” said Atsushi Moriyama, an associate professor of modern Japanese history at the University of Shizuoka.

In Japan many people, particularly nationalists, have maintained Roosevelt provoked Japan into starting the war, as Stinnett’s book argues.

They also argue that Japan fought a war of self-defense against the U.S. because Washington in August 1941 slapped economic sanctions on Japan and banned all oil exports to the country. Japan had no other significant oil suppliers and its army and navy would have used up the nation’s stocks in short order if war broke out.

But in the lead-up to Pearl Harbor, Japan and the U.S. “provoked” each other unintentionally, eventually prompting Japan’s decision to launch the attack, Moriyama said.

In July 1941, Imperial Japanese troops advanced into what was then southern French Indochina, aiming to capture the rich natural sources of Southeast Asia. The Japanese military did not believe the incursion would provoke the U.S., its main oil supplier, into cutting off supplies.

But the U.S. did just that, believing Japan would back down.

The ban eventually provided ammunition to the hardliners among Japan’s top leaders and led Tokyo to decide to wage a reckless war against the U.S. by launching the Pearl Harbor attack, historians argue.

Japan, part of the Axis powers, went on to invade many parts of Asia and the Pacific and inflict horrendous casualties. But the tide of the war turned, and by its end most major Japanese cities had been destroyed by massive U.S. air raids and at least 3.1 million Japanese had been killed.

Japan’s leaders should have been held responsible for the horrible outcome of their decision to wage war against the U.S., whatever their intentions might have been, Moriyama said.

“Some say the U.S. provoked Japan. But politicians should be held responsible for the results of their decisions, and you can’t justify the result of the war,” Moriyama said.

Many Japanese also believe a note handed over to Japan on Nov. 26, 1941, by then-U.S. Secretary of State Cordell Hull contained unacceptable demands, including the withdrawal of Japanese forces from China. This also is seen as having forced Japan’s hand against the U.S.

But both Sudo and Moriyama argue that this widespread belief in Japan is inaccurate because Japan had decided on Nov. 5 to go to war if Washington turned down Tokyo’s concession proposals during bilateral negotiations.

But the U.S. by then had deciphered the Foreign Ministry’s cables and was well aware of Japan’s concession plans and the determination behind them. This means that both Japan and the U.S. were ready for war and Hull’s note was just the last straw, they said.

Sudo believes the U.S., too, bears partial responsibility for creating tensions that eventually led to the Pacific War.

But as far as Pearl Harbor is concerned, Japan should apologize because it launched the attack before declaring war — a clear violation of international law.

Abe plans to pay a floral tribute to the war victims and is expected to deliver a speech emphasizing the importance of reconciliation to both countries. Japanese officials, however, say that he does not plan to extend an apology over the Pearl Harbor attack.

Still, Abe’s visit will be taken as a gesture of apology for Pearl Harbor, Sudo said.

“Even if Abe doesn’t say words of apology, he will dedicate flowers to the war victims. It will be taken as an apology anyway,” Sudo said.

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