To what extent does the policy community of the United States understand that the presence of U.S. forces in East Asia creates incentives for the governments of South Korea and Japan to not resolve their differences -- and that Japan-South Korea tensions are indicators of a relatively benign security environment?
What would prompt Japan and South Korea to lay aside or better yet tackle their disputes over Dokdo, the sex slaves of the Japan Imperial Forces (a.k.a. the "comfort women") and the history of the colonial period?
a) China turning truly evil and dangerous
b) Russia turning truly evil and dangerous
c) North Korea having a truly crazy government and important military capabilities
d) the U.S. really pulling its forces out of the region
As for d), those ruling Japan and South Korea have done the math. If the governments and elites of the two countries get along, then Washington's dreaded "burden sharing" kicks in. If the two sides remain divided, U.S. forces have to stay in the region in pretty much their current form and numbers -- which is not only what the democratic governments of South Korea and Japan want (cheaper, it is) but what all persons of sense inside China want, a massive U.S. presence restraining the crazies inside the PRC from doing anything really stupid.
So the collapse last year of the intelligence sharing agreement in between Japan and South Korea (Link)? An opportunity to mess matters up mercifully missed.
A pulling back from the pantomime dispute over the sovereignty of Dokdo? To be avoided.
Work hard to stop Japanese textbook publishers to stop using weasel words in descriptions of the colonial period and South Koreans to stop playing the historical victim card? Probably not the best use of one's time.
On the matter of the sexual slavery, those who are the guardians of Japan's interests should, but probably will not, present the options on what to do to the people of Japan. For the governments, the incentives are not in favor of reconciliation. Individual citizens of free societies are perhaps incentivized differently.