In the spring of 2012 when the issue of so-called "comfort women" was reignited between Japan and South Korea, the Japanese government of then Prime Minister Yoshihiko Noda presented a proposal to Seoul aimed at resolving the matter, it was learned by Sunday from former senior officials of both countries.

The informal proposal featured apologies to all the surviving victims by the Japanese ambassador as well as Japanese government-funded humanitarian measures, according to the officials.

(A statue of a girl symbolizing the issue of "comfort women," who worked in Japanese wartime military brothels, in front of the Japanese Embassy in Seoul.)

While South Korea has long called on Japan to acknowledge state responsibility for wartime Japanese military brothels, Tokyo argued that the proposal amounted to an admission of "public responsibility" for the issue.

A former senior South Korean official said Seoul countered that it would accept the deal even if Tokyo did not explicitly admit state responsibility, provided it did not deny such responsibility. Ultimately, however, the two sides were unable to bridge their differences.

Then South Korean President Lee Myung Bak's landing on a pair of islets disputed between the two sides in August of that year, which drew an angry response from Japan, effectively nixed any chance of the proposal moving forward. The South Korean-controlled islets in the Sea of Japan are known as Takeshima in Japan and Dokdo in South Korea.

At the end of 2015, the Japanese government under Prime Minister Shinzo Abe and the administration of then South Korean President Park Geun Hye reached a landmark deal to "finally and irreversibly" settle the comfort women issue.

The deal featured a foundation which was put in charge of handing out cash payments to the victims and their families from a 1 billion yen (about $8.8 million) fund provided by Japan.

However, there was no direct apology, and the opportunity for a Japanese government representative to apologize in front of the victims was lost.

According to a Japanese Foreign Ministry official, in March 2012, Vice Foreign Minister Kenichiro Sasae visited South Korea during which he sought a resolution to the contentious issue with a three-pronged proposal.

Specifically, he proposed a Japanese government-funded humanitarian measure, individual apologies to the victims by the Japanese ambassador, and an apology by Noda to Lee as well as an announcement of the humanitarian measure at a summit meeting.

At the same time, Sasae communicated that there was no change in Tokyo's official position that the matter of compensation for the women was settled under the 1965 treaty that normalized relations. As the humanitarian measure, construction of a monument to the women rather than payments to the victims was planned.

On April 20 of that year, Tsuyoshi Saito, who was deputy chief Cabinet secretary and involved in talks with Seoul, held negotiations on the proposal at the South Korean presidential office with Chun Yung Woo, Lee's national security adviser.

Saito said he sought understanding that the appropriation from the Japanese government and Noda's apology together amounted to "an admission of public responsibility," but received no reply.

Chun for his part said that Seoul proposed accepting the offer provided Tokyo agreed to the condition of not denying that the government-funded assistance was tantamount to recognition of state responsibility.

"The president also signed off on this policy, but Mr. Saito rejected it," Chun said.

Saito insists that there was "no such condition," and points out that the failure to reach a deal led to the deterioration of the relationship.

Chun echoed that view, saying, "If an agreement had been reached, the president's trip to Dokdo would not have gone ahead."