Four Chinese and four Russian military planes entered South Korea's air defense identification zone without notice Tuesday, Seoul's military said, prompting the South Korean Air Force to send its fighter jets to the scene.

The Joint Chiefs of Staff said that between 11:52 a.m. and 1:49 p.m., the Chinese and Russian aircraft entered the southern and eastern parts of the KADIZ, respectively, and exited it. They did not violate South Korea's air space, it added.

"Our military identified the Chinese and Russian planes before their entry into the KADIZ and deployed Air Force fighters to conduct tactical steps in preparation against potential accidental situations," the JCS said in a text message sent to reporters.

Their entry into the KADIZ came after the defense chiefs of South Korea, the United States and Japan highlighted their commitment to strengthening trilateral security cooperation on the margins of the Shangri-La Dialogue, an annual security conference in Singapore, over the weekend.

The air defense zone is not territorial airspace but is delineated to call on foreign planes to identify themselves so as to prevent accidental clashes. (Yonhap)