Japan has agreed to pay 1 billion yen ($8.3 million) to help the Republic of Korea set up a fund to support Korean women forced into sexual slavery by the Japanese army before and during World War II, in order to settle the "comfort women" issue.

Later, during his talks with ROK President Park Geun-hye over the phone, Japanese Prime Minister Shinzo Abe said the deal was "final and irreversible" and rendered apology to the Korean women who were forcibly "recruited" as sex slaves. Park, on her part, said she expected the agreement to help develop bilateral relations in a stable manner with an eye to the future.

For many, it is surprising to see the sudden settlement of the sore point in Tokyo-Seoul relations, although some uncertainties remain. To begin with, the deal is actually a compromise between Japan and the ROK in which the United States seems to have played a vital role. US Secretary of State John Kerry welcomed the agreement on the very day it was announced, saying it "will promote healing and help to improve relations between two of the US' most important allies". Applauding the leaders of the two countries "for having the courage and vision to reach this agreement", he even urged the international community to support it.

Apparently, the last thing Washington wants to see is its "pivot to Asia" falling apart because of the widening fissures between its allies in East Asia, and this could explain its consistent intervention in Japan-ROK bilateral affairs.

Failing to make progress in some longstanding territorial disputes and convince its neighbors of its "sincere" remorse over its war crimes, Japan had been caught in a diplomatic stalemate and was thus desperate to seek a diplomatic breakthrough. As much as Abe hates to admit, reconciling with the ROK was a decision he was forced to make because his extensive diplomatic maneuvers over the past two years had not been able to end its "neighborhood dilemma".

Besides, the Abe administration needed to settle the "comfort women" issue with the ROK to enhance its chances of winning the upper house election in July. His ruling Liberal Democratic Party may greatly benefit from the deal on a sensitive historical issue by gaining public support and neutralizing the opposition parties' accusation that Abe is not competent enough to pursue better relations with Japan's neighbors.

However, the rapprochement between Japan and the ROK is neither final nor irreversible, because some embedded uncertainties could keep haunting East Asia. Many in the ROK, especially the surviving "comfort women" such as the 88-year-old Lee Yong-soo have rejected the deal. Lee said she would ignore the agreement and urge Japan to provide legal compensation for the victims if Abe truly wants to resolve the issue.

The Korean Council for the Women Drafted for Military Sexual Slavery by Japan, known for installing the statue of a girl symbolizing the "comfort women" in front of the Japanese embassy in Seoul in 2011, has also denounced the deal.

In fact, the "comfort women" issue is not just about the ROK and Japan, because the estimated 200,000 victims were from not only the Korean Peninsula, but also China, Southeast Asian nations, Russia and other countries.

In other words, the issue can be settled only when Japan sincerely reflects upon the atrocities it committed in other countries more than seven decades ago. Japan still has a mountain to climb in this regard, as well as other issues such as the attempts by many Japanese politicians, including Abe, to revise Japan's wartime history.

Since some Japanese right-wing politicians are yet to face up to their country's past, the Japan-ROK deal on the "comfort women" issue cannot be seen as Japan's genuine repentance and remorse. At best, it is an act of Abe's political expediency.

The author is an associate researcher at the Japan Studies Center of the Chinese Academy of Social Sciences.