Progress in repairing ties between North and South Korea has prompted concern in Tokyo that Seoul may rush into dialogue with Pyongyang at the expense of the "maximum pressure" campaign espoused by Japan and the United States.
"South Korea might run off ahead on a course of dialogue," a senior Foreign Ministry official said in the wake of Saturday's talks in Seoul between South Korean President Moon Jae-in and a high-level North Korean delegation at the Pyeongchang Winter Olympics' Opening Ceremony a day earlier.
The delegation gave Moon a letter from North Korean leader Kim Jong Un inviting him to visit the North, a day after Prime Minister Shinzo Abe said he and Moon had reaffirmed their shared stance of maximizing pressure on Pyongyang until it scraps its nuclear weapons program.