It came after the North test-fired another ballistic missile on the weekend, its eighth missile launch this year alone.

Lee pointed out that the North's nuclear and missile development is posing a grave threat to peace and stability not only on the Korean Peninsula but also in the international community.

He stressed the need for closer coordination among the three countries than any other time.

In response, Dunford said they should maintain a "fight tonight" posture on the basis of close partnerships, a view echoed by Japan's JCS chief, according to Lee's office.

Their video conference is of significance in that "ways for substantive cooperation" among the regional powers were discussed in response to the North's back-to-back provocations, it added.

In a separate statement, the US military also said the JCS chiefs talked about trilateral defense cooperation measures to tackle increasing North Korean nuclear and missile threats.

"The discussions reflected three countries' desires to enhance trilateral defense communication and cooperation and deepen their understanding of a unified vision of peace and stability in the region," it said. The military chiefs agreed to coordinate further on mutual security. (Yonhap)