A former American ambassador to Seoul said this week that ties with South Korea and Japan were both very important for the U.S., dismissing views that Washington is prioritizing its alliance with Tokyo. In an interview with a local news agency here, Stephen Bosworth said the strength of the U.S.-South Korea relationship “is very much a part of our assessment of our future strategy in all of East Asia.”

His remarks might have been nothing new, but appeared to draw some reassurance ― or skepticism ― from South Koreans, who now see Japanese Prime Minister Shinzo Abe substantiating his vision for resetting Tokyo’s postwar posture during his ongoing visit to the U.S. What perplexes Seoul is that Washington is ready to accept to some extent Abe’s historical revisionism ― or selective amnesia of Japan’s militarist past ― in reward for his full cooperation with Washington’s efforts to keep a rising China in check.

Foreign and defense ministers from the U.S. and Japan reached a deal on expanding Tokyo’s military role abroad during their meeting in New York a day before Abe held summit talks with President Barack Obama at the White House on Tuesday. In a joint vision statement, the two countries pledged to work closely together to tackle global challenges, saying their fates were “intertwined” and “inseparable.” Obama and Abe also agreed to accelerate the conclusion of the Trans-Pacific Partnership, which will not include China.

Abe’s U.S. visit culminated in his address to a joint session of Congress on Wednesday. He became the first Japanese prime minister to be given the honor, but his closely-watched speech stopped short of making a clear apology for Japan’s pre-1945 wartime atrocities, including the sexual enslavement of Korean and other Asian women for imperialist Japanese soldiers in frontline brothels.

The strengthening of the partnership between Washington and Tokyo amid Abe’s backpedaling on historical issues poses a diplomatic conundrum for Seoul. It may be inevitable for South Korea to avoid remaining out of sync with U.S. moves to bolster trilateral security cooperation with its two key Asian allies. As some experts here note, the revised guidelines for defense cooperation between the U.S. and Japan may help deter evolving threats from North Korea.

The upgraded three-way security cooperation may be a cause of concern for China, but should also lead Beijing to put more pressure on Pyongyang to refrain from making provocations and become more sincere toward discarding its nuclear arsenal.

Seoul officials need to be more sophisticated and far-sighted in going ahead with their two-track approach of separating historical disputes with Tokyo from security and economic cooperation between the two sides. In the course, they still could and should continue to argue that Abe’s refusal to acknowledge Japan’s wartime atrocities will not serve to carve out Tokyo’s due roles and status in the international community.