BEIJING, Dec. 30 -- The agreement between South Korea and Japan on the issue of "comfort women," which shows what a Japanese expert called "strategic ambiguity," reflects apparent differences between the two sides and a lack of sincerity in reaching the deal.

South Korea and Japan reached a "final," "irreversible" agreement on Monday over Japan's sex slavery of Korean women during WWII. Japanese Prime Minister Shinzo Abe offered an apology in a letter read by his Foreign Minister Fumio Kishida while his country paid 1-billion-yen (about 8.3-million-U.S.-dollar) to those Korean sex slaves.

"Both sides did all they could for strategic ambiguity without compromising on their basic positions," Kunihiko Miyake, research director at the Tokyo-based think tank Canon Institute for Global Studies, was quoted by Kyodo as saying.

Miyake noted that Kishida referred to "responsibilities" during Monday's talks with his South Korean counterpart Yun Byung-se, whereas then Prime Minister Junichiro Koizumi used the term "moral responsibilities" in a letter he sent to former comfort women in 2001.

"The deal made Japan admit its responsibility only indirectly and allowed it to avoid formal legal responsibility," Chosun Ilbo, a major daily, said in an editorial.

The absence of the adjective "legal" in the agreement has prompted discontent and anger among civil groups and former "comfort women" in South Korea.

Denouncing the deal as a "diplomatic collusion" between the two governments, some civic groups argued that Japan should have offered a clearer apology and acknowledged its legal responsibility for the atrocity, Yonhap reported.

Besides, the wording of the 1 billion yen (8.3 million dollars) by the Japanese side also shows ambiguity and reveals a divergence between the two sides.

While some might interpret Japan's pledge to allocate the funds from its national budget as the country agreeing to pay government compensation to the 46 surviving Korean victims, the Japanese foreign minister denied this was the case.

Kishida said the latest pledge did not constitute compensation, maintaining Japan's view that such matters had been completely settled and finalized under the 1965 treaty that restored diplomatic ties and was accompanied by more than 800 million dollars in economic aid and loans from Japan to South Korea.

In addition, the agreement does not stipulate a deadline for Japan to pay 1 billion yen to the envisaged South Korean government-run foundation, and it's not yet known when the foundation will be launched, said Hideshi Takesada, a professor of Korean affairs at Takushoku University in Tokyo, as quoted by Kyodo.

Japan would find it difficult to implement the deal if the South Korean government fails to convince civic groups to remove a statue of a girl symbolizing the victims located in front of the Japanese Embassy in Seoul, Takesada noted.

The details of the fund remain unclear, and the new fund could run the risk of being rejected again like on earlier occasions, said Haruki Wada, former executive director of the now-defunct Asian Women's Fund, which was initially set up to provide "atonement money" to the victims.

Calling it a "surprise deal," the Associated Press said both sides compromised and neither got everything it wanted.

The so-called "final," "irreversible" deal apparently attempts to solve the long-standing thorny issue once and for all, but with so many details unclarified, differences still remain between the two sides and await to be further addressed.