Tokyo is looking into reopening official talks with North Korea to resolve questions over the abductions of Japanese citizens decades ago, raising concerns among allies who fear Tokyo's focus on that issue might weaken efforts to rein in Pyongyang's nuclear weapons programme.
Chief cabinet spokesman Yoshihide Suga said that high-level talks with North Korea were possible if they would lead to a breakthrough on the abductions.
Prime Minister Shinzo Abe has indicated he is open to holding a summit with North Korean leader Kim Jong-un if such a breakthrough could be made.
Abe sent a senior adviser to Pyongyang last week, catching Seoul and Washington off guard. Both said they were not given prior notice.
Washington and North Korea's neighbours have been stepping up their pressure on Pyongyang since it conducted a rocket launch and its third nuclear test this year.
For Tokyo, the abductions have long been a key priority and are the biggest obstacle to resuming official talks, which have been stalled since last November.
But Glyn Davies, the US special representative for North Korea policy, warned Pyongyang might be trying to use talks with Japan to divide Tokyo, Washington and Seoul.