The White House has announced that U.S. President Barack Obama will include South Korea in his Asian trip in April. President Park Geun-hye and her foreign policy lieutenants did not conceal their contentment in having successfully persuaded the U.S. leader to change his original travel plan that included only Japan, Malaysia and the Philippines.

If the current relations between South Korea and Japan and their effect on the region were not considered, Park and her aides might not care that much about whether or not Obama comes to Seoul this time. The U.S. president has already visited Seoul three times on top of summit talks with Park in Washington last May. The two leaders are also expected to meet again in Beijing in October at the Asia-Pacific Cooperation summit.

But Park and her foreign policy officers may well believe that in view of the current situation in Northeast Asia, specifically Tokyo’s worst relations in years with both Seoul and Beijing, the U.S. president could give the “wrong message” if he visits only Tokyo. In addition, Obama’s decision to visit Seoul again could demonstrate to North Korea a strong U.S. alliance with South Korea.

Therefore, Obama’s decision to visit Seoul is good news to the South Korean government. But what really matters is how the U.S. leader perceives the situation here and what position he should take.

In that context, it was disappointing that U.S. Secretary of State John Kerry commented to the effect that both sides are to blame for the current rows between South Korea and Japan. Kerry said during his visit to Seoul last week that it is “up to Japan and Korea to put history behind” them and move relations forward. He did express hope that the U.S. could mediate the disputes, but it is clear that the U.S. essentially seeks a neutral stance between its key allies.

The United States cannot mediate a settlement without correct perception of the situation. Much of the current tension in Northeast Asia was caused by Tokyo’s failure to acknowledge its wartime wrongdoings such as its military sex slavery, pursuit of rightist nationalism and military expansionism. As the key balancer in the region, the U.S. should no longer turn away from Japan’s immature bullying. Sidestepping the issue would only bolster criticism that the U.S. is giving tacit approval to a stronger Japan in order to rein in China’s growing power.

Kerry said in Seoul that positive relations between Japan and its neighbors are in the best interests of the U.S. and the region, and that it is critical to forge robust trilateral cooperation, particularly in the face of North Korea’s nuke threat.

Any such cooperation would not be possible if Japan refuses to change and if it tries to maintain good relations only with the U.S. It might be too tall an order for Obama to tell Japanese Prime Minister Shinzo Abe in unequivocal terms to come to his senses, make correct recognition of its wartime past and atrocities, renounce nationalism and restore relations with neighbors.

But for now the U.S. is the only one Japan will listen to, and Obama should try to at least tame the unruly Abe, which would work in the best interest of the U.S. as well as all the other parties in the region. We deem it to be a good sign that both the U.S. State Department and the U.S. Embassy in Tokyo expressed “disappointment” in official statements when Abe visited the war shrine last December.