(ATTN: UPDATES with details from 2nd para)
SEOUL, Dec. 27 (Yonhap) -- A Chinese military jet entered South Korea's air defense zone Thursday without notice, defense authorities here said.
The aircraft entered the country's air defense identification zone, called KADIZ, at around 10:21 a.m. from an area near Jeju Island and Ieo Island and exited it half an hour later, according to the Joint Chiefs of Staff (JCS).
It again crossed into the KADIZ at around 11:54 a.m. and flew along South Korea's east cost before leaving it at around 3 p.m., the JCS added.
A Chinese military plane also entered the area a month earlier.
A section of the KADIZ overlaps with the air defense zones designated by China and Japan, a source of potential tension among the regional powers.
South Korea's military officials say China's move is aimed at testing responses by Seoul and Tokyo.
An air defense identification zone, or ADIZ, is an area of the skies declared by a state for the early identification and location of foreign planes approaching its territory. It is not defined in any international law or treaty.
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