Top envoys from South Korea, the U.S. and Japan warned North Korea not to take further provocative steps at talks in Washington early this week. The three countries agreed to make “united and effective” efforts to prevent the North from making further provocations, according to South Korea’s top nuclear envoy Hwang Joon-kook, who provided a briefing on the results of the meeting with his U.S. and Japanese counterparts.

It was a rare show of unity between Seoul and Tokyo, which have long been at odds over territorial and historical issues. The trilateral discussion on North Korean issues, the first in five months, was a follow-up to an agreement made by the leaders of the three countries last month. U.S. President Barack Obama had hosted a summit with South Korean President Park Geun-hye and Japanese Prime Minister Shinzo Abe on the sidelines of an international nuclear security forum in The Hague in a bid to help improve the strained ties between Washington’s two key Asian allies.

The U.S. State Department said after this week’s talks that “these discussions reflect the close ongoing cooperation between our three countries, as well as our common values and interests across the Asia-Pacific region.” The remarks, however, seemed to mainly reflect Washington’s wishes, detached from the actual state of Seoul-Tokyo ties, which have deteriorated since the three-way summit.

Japan angered South Korea last week by issuing a foreign policy paper that renewed its claim to South Korea’s easternmost islets of Dokdo and approving school textbooks revised to promote its territorial stance. Days earlier, Tokyo lifted a self-imposed ban on weapons exports that had been in practice since 1967, in a move that could unnerve its neighbors.

What recent events suggest is that Seoul is seeking to take a dual approach in dealing with Tokyo, separating sensitive historical and territorial matters from security cooperation. It may be a realistic and inevitable option for South Korea in the face of growing threats from the unpredictable regime in Pyongyang.

Seoul officials are now tasked with exercising the strategic wisdom of using international opinion and close cooperation with China to settle thorny issues with Japan, while strengthening a united front against North Korea.