Japanese Prime Minister Shinzo Abe is in Washington this week. His visit is designed to look ahead to the future of U.S.-Japanese relations, with discussion of increased security cooperation a key item on the agenda, as well as relations with China and trade. In a historic moment, Abe will also become the first Japanese leader to address a joint meeting on Congress on Wednesday.

Yet, for all the talk of the future surrounding the trip, the past hangs heavy over the Japanese leader's visit. In fact, despite Abe's best intentions, the narrative isn't the history being made by the visit, but the history many feel has been repeatedly dismissed by Abe.

Now pressure is building for Abe to make a public apology for Japan's worst cruelty committed during World War II during his visit, with 24 members of the House of Representatives signing one letter that called on Abe to "reaffirm and validate" previous apologies made by Japanese leaders.

But if Japan has apologized before, why would it need to apologize again for events that happened 70 years ago? Here are some of the factors at play.

Japan's 'Comfort Women' problem

Before and during World War II, Japanese soldiers kept tens of thousands of girls and women in Korea, China and elsewhere in Asia as sexual servants. Some estimates suggest that as many as 200,000 women were forced to serve in "comfort houses" (as the military's brothels were euphemistically called) and that the Japanese army subsequently killed large numbers of these women.

After evidence was discovered linking military authorities with the brothels, Japan officially apologized for the wartime brutality shown to "comfort women" in 1993, and set up the Asian Women's Fund to provide compensation for the victims who are still alive. But there was lingering discomfort over the apology in Japan, where some right-wingers argued that the women had largely been prostitutes, acting of their own free will.

Abe, who has a reputation as a revisionist, has himself at times suggested that these women were not coerced into relations with Japanese soldiers, though in a recent interview he told The Post that his "heart aches" when he realizes the "immeasurable pain and suffering beyond description" these women went through. His critics, however, say his government has overseen a slow shift to a revisionist history: For example, recently pressuring McGraw Hill, an American publisher, to remove two paragraphs about comfort women from a college textbook (McGaw Hill refused the request). It appears to be just one instance of the official narrative of the war shifting within Japan.

Now groups such as the Washington Coalition for Comfort Women Issues are calling for Abe to issue a definitive, unequivocal apology to comfort women. “We do want Abe to acknowledge what happened and issue an official apology," Junhsil Lee, a Korean-American who lives in Rockville and formed the coalition, told The Post. "Then we will be glad to dissolve our organization and move on.”

The anger from American veterans

Abe is also facing pressure from groups like American Defenders of Bataan and Corregidor Memorial Society who advocate for World War II prisoners of war. That group is among those that have criticized House Speaker John A. Boehner's decision to invite Abe to visit Congress on the birthday of Emperor Hirohito, Japan's ruler during World War II.

"On that day, American POWs were forced to bow the lowest in Imperial Japan's prison camps," a letter sent to Boehner by the group read, according to National Journal. "There are many in Japan who believe that the War was just and who deny the record of Japan's many wartime atrocities. We fear the scheduling of Prime Minister Abe's speech offers comfort to deniers and insults America's Pacific War veterans."

Edward Jackfert, a 93-year-old who was held by the Japaneses as a POW in the Philippines, also criticized the timing of Abe's speech in an article in the Diplomat. "Imperial Japan was a brutal regime that was merciless to the people put in its care. It astonishes me that Japan’s leaders now avoid offering an apology or acts of contrition," Jackfert wrote. "Yet, if the U.S. Congress cannot remember this history, it is unlikely that the Japanese will want to disturb that amnesia."

Japan held around 36,000 prisoners of war from the Allied powers during World War II, many of them kept in extreme and inhumane conditions. The POW Research Network Japan says that as many as 27 percent of those prisoners died, a considerably higher mortality rate than found among prisoners held by Germany or Italy.

While Japan has apologized for its treatment of POWs in the past, critics ask that Abe might use his Congress speech to offer a further concrete apology: The American Defenders of Bataan and Corregidor Memorial Society hopes that Japan will install monuments to American war dead inside of Japan.

Abe's unclear stance

Japan has apologized for its World War II misdeeds in various forms before, most notably the 1995 Murayama statement which apologized for the damage caused by Japan's "colonial rule and aggression.” Abe has publicly lent support to those apologies, telling Japan's parliament earlier this year that he “upholds the position of previous cabinets regarding recognition of history as a whole."

These comments have been vague, however, and there has been intense speculation about how he will actually mark the 70th anniversary of the end of the war in August. In many ways, Abe's address to Congress is being interpreted as a practice run for this more important moment later this year: Any apology or lack-thereof in August could be a major moment in relations between Japan and its Asian neighbors. It may also say a lot about how Abe views the future of Japan's military.

Jennifer Lind, an associate professor of government at Dartmouth College and a faculty associate at the Reischauer Institute for Japanese Studies at Harvard University, says that Abe has shown some flexibility with regards to history: After criticism from the United States and others, he has toned down his visits to the controversial Yasukuni Shrine, for example, sending offerings rather than visiting.

Yet the Japanese leader appears to be rejecting demands to apologize again. "This represents an effort to assume a compromise position between right and left," Lind says, "between domestic and international audiences." Whether that balancing act can last is unclear, however.

See also:

Abe urged to uphold Japan’s apology for wartime aggression

Shinzo Abe’s optimistic vision

How Justin Bieber inadvertently stepped into one of the world’s greatest geopolitical controversies