(ATTN: UPDATES with details in last 4 paras; ADDS photo)
SEOUL, Dec. 18 (Yonhap) -- Five Chinese military planes on Monday entered the Korean Air Defense Identification Zone (KADIZ), prompting South Korea's fighter jets to make an emergency sortie, Seoul's military said.
The Chinese aircraft were detected infringing on the KADIZ from the southwest of Ieo Island at around 10:10 a.m. and flying out of the zone at 1:47 p.m., according to the Joint Chiefs of Staff.
"Our military confirmed that they are military planes of China through the Air Force's Master Control and Reporting Center," it added.
The South's fighters took "normal tactical measures" until the Chinese planes left, it said.
Its F-15K and KF-16 fighters were mobilized for a possible contingency.
The Chinese planes included two bombers, two fighter jets and a reconnaissance plane, a JCS official told reporters.
"We talked with the Chinese side over a hotline and it said the operation was part of a routine exercise," he said. "We are analyzing its exact intention."
The KADIZ near Ieo Island overlaps the air defense zones unilaterally designated by China and Japan.