IN May, President Barack Obama and Japanese Prime Minister Shinzo Abe visited Hiroshima, where the United States dropped an atomic bomb in 1945 and soon compelled Japan's surrender, ending World War II. It was a historic moment:

Obama was the first sitting U.S. president to visit the city.

Now, Abe is repaying the favor.

On Tuesday, he will accompany Obama to Pearl Harbor, the site of the Japanese attack 75 years ago that led the United States to join World War II.

But is Abe's visit quite as historic? When it was announced in early December, a Japanese Foreign Ministry official said Abe would be the first sitting Japanese leader to visit Pearl Harbor since World War II. News outlets repeated this assertion, including The Washington Post.

But quickly afterward, things began to look a little more complicated. The Yomiuri Shimbun newspaper soon reported that Prime Minister Shigeru Yoshida had stopped in Hawaii, home to Pearl Harbor, in 1951 when flying back home from San Francisco. He made a public visit to the National Memorial Cemetery of the Pacific, which honors American war dead, and a more private visit to Pearl Harbor.

The Pearl Harbor visit was not noted widely by the U.S. press, but it appeared in the Japanese press.

Yoshida told a reporter from the Yomiuri Shimbun that he had been "moved" by the visit. It also turns out that the U.S. Pacific Fleet commander at the time, Adm. Arthur Radford, was present.

Radford later wrote that the visit was awkward for Yoshida and that they mostly discussed his dog.

Now more developments indicate that Abe may not be the second sitting prime minister to visit Pearl Harbor, either. Last week, the Hawaii Hochi - a dual-language Japanese-English newspaper based in Hawaii - suggested that two other Japanese leaders may have visited Pearl Harbor in the 1950s.

The newspaper posted images to its Facebook account that showed two front pages from its archive. One claimed that Ichiro Hatoyama visited the harbor on Oct. 29, 1956, where he was welcomed by a 19-gun salute and a band performing Japan's national anthem. Another headline says that Nobusuke Kishi, Abe's grandfather, visited the harbor on June 28, 1957, where he laid a wreath at the flagpole at the National Memorial Cemetery of the Pacific.

The Japanese government has now been forced to change its story. After Yoshida's visit to Pearl Harbor was made public again, the government asserted that as the USS Arizona Memorial in Pearl Harbor was not constructed until 1962, Abe will still be the first to visit the most famous monument. "He will also be the first to do so with an American president," Chief Cabinet Secretary Yoshihide Suga told reporters.

Sheila Smith, a senior fellow for Japan studies at the Council on Foreign Relations, says she was "taken aback" by the initial mistake. "If any organization should know its history, its MOFA," she wrote via email, using an acronym to refer to the Japanese Foreign Ministry. "I'm also surprised that Abe himself or rather his office didn't correct the record as he is a careful student of his grandfather's diplomacy towards the U.S."

But perhaps a bigger question, Smith suggested, was why a sitting Japanese leader had visited three times in the 1950s and never since. "I suspect that had to do with domestic Japanese politics," she says, noting that the security treaty between the two nations was revised in 1960. "The 1960s ushered in a new era of economic dynamism and a newfound sense of progress in Japan. Perhaps continued Pearl Harbor visits were seen as looking backwards instead of looking ahead."

Domestic opinion has forced Japanese leaders in the past to cancel plans to visit Pearl Harbor: In 1994, Emperor Akihito was forced to walk back a planned visit to the memorial after widespread protests in the Japanese media, which viewed it as an apology.

"The more important point is that this is treated and celebrated as the 'first' - clearly the Japanese prime ministers' visits in the past were not considered as significant then," Yaguchi Yujin, an expert in Japan-U.S. history at the University of Tokyo, said in an email. "That this visit by Abe is regarded as something seminal (and generally quite positively received) by the Japanese media shows, I think, how the war between the two nations is remembered today."

Yujin says that for many in Japan, Pearl Harbor is seen as the beginning of the process that resulted in the atomic bombings of Hiroshima and Nagasaki - a mistaken belief, he suggests. "Japan had been fighting wars prior to 1941 but that part of history is marginalized, if not erased, as a result of this kind [of] celebration of a binational conflict," he says.

Still, despite the convoluted history, Abe's visit will have one characteristic in common with Obama's visit to Hiroshima: Like the U.S. president, he has no plans to apologize.