TOKYO — In the courtly world of diplomacy, the meeting between Defense Secretary Chuck Hagel and President Park Geun-hye of South Korea was something of a shock.

Mr. Hagel was in the region to try to revitalize America’s faltering “pivot” to Asia and had one especially pressing request for Ms. Park: to try to get along better with Japan. The steely Ms. Park instead delivered a lecture about Japan’s “total absence of sincerity” over the suffering that imperial Japan caused Korea in the last century and finished with a request of her own: that Washington force Tokyo to behave.

“If Germany had continued to say things that inflicted pain, while acting as if all was well, would European integration have been possible?” she asked Mr. Hagel. “I think the answer is no.”

Ms. Park’s refusal to budge during that September meeting was one of many recent reminders that the leaders of Japan and South Korea, the United States’ closest military partners in Asia, seem to be barely on speaking terms. Analysts say the current tensions are among the worst in recent years, an increasingly vexing problem for the Obama administration as it struggles to present a united front in dealing with a rising China and a nuclear North Korea.