The United States, Japan and South Korea said on Tuesday they activated a real-time North Korea missile warning data sharing mechanism and established a multi-year plan for trilateral exercises.

Previously, Secretary of Defense Lloyd Austin, Japan Minister of Defense Kihara Minoru and South Korea Minister of National Defense Shin Wonsik agreed to finalize these initiatives by the end of the year during a November trilateral ministerial meeting.

A Dec. 19 trilateral defense ministerial joint statement released by the U.S. Defense Department said the mechanism was activated after recent tests that verified the data sharing mechanism achieved full operational capability.

“The three countries established this mechanism to improve their ability to ensure the safety of their peoples by trilaterally detecting and assessing missiles launched by the DPRK in real-time,” DoD said in a statement.

The countries also enacted a multi-year trilateral exercise plan set to start in early 2024. DoD said they have made progress improving quality and quantity of their exercises in the past year and this new plan will regularize these exercises and “execute them more systematically and efficiently moving forward.”

The activation follows North Korean ballistic missile launches on Dec. 17 and 18.

“These achievements and other ongoing efforts demonstrate the unprecedented depth, scale, and scope of trilateral security cooperation by the United States, the Republic of Korea, and Japan. The three countries will continue to build upon their cooperation to respond to regional challenges and ensure peace and stability on the Korean Peninsula, in the Indo-Pacific, and beyond,” DoD added.

Also on Tuesday, Assistant Secretary of Defense for Indo-Pacific Security Affairs Ely Ratner spoke to South Korean Deputy Minister for National Defense Policy Heo Tae-keun and Japan Director-General for Defense Policy Kano Koji, reaffirming U.S. extended deterrence commitments to both countries.