Japan's Prime Minister Shinzo Abe, second from left, is led by a Shinto priest in December 2013 as he visits Yasukuni shrine, viewed by other Asian nations as a symbol glorifying Japanese militarism. (Toru Hanai/Reuters)

In the 1930s and 1940s, a legion of women across Asia were coerced from their homes, often with promises of jobs in factories or restaurants, and installed on the battlefront, where they were forced to have sex with Japanese soldiers. Most of the women were between 14 and 18. Some say they were raped dozens of times a day.

Two decades ago, Japan apologized for the system and the “immeasurable pain” it caused. But rather than salving the wounds of victims, the apology has drawn increasing scorn from a powerful segment of Japanese, who call it a regrettable political concession made without evidence of the Imperial Army’s complicity.

That sentiment, once held by an extreme right-leaning minority, has edged into Japan’s mainstream and has fed the latest spike in animosity between Tokyo and its neighbors, particularly South Korea.

Prime Minister Shinzo Abe’s government said Feb. 28 that it would reexamine the evidence that prompted the 1993 apology, known as the Kono Statement. Although Japan didn’t say whether it would water down or revoke the apology, government officials in Seoul fear that the move is being driven by Abe’s personal views. Abe said in 2007 that there was “no evidence” to prove that the women were coerced into serving as sex slaves — a view that is contested by most historians and is in opposition to the testimony of victims and other witnesses.

If Japan reopens the case, it would mark perhaps the most provocative element of Abe’s agenda, one that includes the easing of restrictions on Japan’s Self-
Defense Forces and curriculum changes intended to boost national pride among students.

On Wednesday, South Korean Foreign Minister Yun Byung-se accused Japan of adding “insult to the honor and dignity of those victims who had weathered physical and psychological pains.”

“It’s appalling that the Abe government is taking up this initiative,” said Yoon Mee-hyang, a representative of the Korean Council for the Women Drafted for Military Sexual Slavery by Japan. “Some of the victims have told me they wish they weren’t alive to see this.”

Within Japan, reexamining the Kono Statement could play to an influential group of conservative media members and lawmakers. The head of Japanese public broadcaster NHK said in January that the sexual slavery network was wrong only by “today’s moral values.” Last month, Toshio Tamogami, a candidate for governor of Tokyo, said on the campaign trail that the system, known euphemistically as the “comfort women” system, was a Korean fabrication. Tamogami received a better-­than-expected 12 percent of the vote.

According to scholars, as many as 100,000 women — Koreans, Filipinos and Taiwanese, among many others — were exploited by Japanese soldiers for sex. They served in “comfort stations” across the region, from Burma to the Siberian border.

Japanese who oppose the Kono Statement say there is no documentation proving that the military created the system with orders from on high. But that argument puzzles South Korean officials, who note that Japan’s Imperial Household Ministry gave orders to burn sensitive wartime documents at the time of the country’s World War II surrender.

At minimum, the testimony of former sex slaves suggests that Japan’s army was responsible for large parts of the system, in some instances setting up brothels and in other instances dealing with private proprietors. Some women say they were recruited by military members, others by brokers. In many cases, Japan’s military provided security and doctors at comfort stations. As Japan advanced through Asia, some women were transported on Japanese navy ships.

When Japan began investigating the comfort-women system in the early 1990s, it gathered testimony from 16 victims, all Korean. Their testimony remains classified.

Reviewing the Kono Statement “would create major controversy” internationally, said Hiroshi Nakanishi, a professor of international politics at Kyoto University. “I think the Japanese government should handle this with a consideration of the impact in mind.”

Particularly since Abe returned to power in December 2012, Japan has become more willing to antagonize its neighbors, and Abe late last year visited a war shrine viewed by other Asian nations as a symbol glorifying past Japanese militarism. Some analysts say the nationalist sentiment has gained traction in Japan amid concerns about China’s economic and military might and, to a lesser degree, the economic success of South Korea.

Tensions between Japan and its neighbors have rekindled historical disputes, not just about the use of comfort women but also about contested territory.

The acrimony between South Korea and Japan is unlikely to lead to armed conflict, but it poses problems for Washington, which depends on those governments to cooperate in dealing with China and North Korea. Daniel Russel, the State Department’s assistant secretary for East Asian and Pacific affairs, said Tuesday in congressional testimony that tensions between South Korea and Japan should be “reduced quickly.”

Yoonjung Seo in Seoul and Yuki Oda in Tokyo contributed to this report.