Two Chinese fighter jets flew through the overlapping parts of the air defense identification zones of South Korea and China earlier this week, prompting the military here to put its warplanes on standby, officials here said Friday.

Their flight on Thursday came just before the Pentagon announced Defense Secretary Lloyd Austin will visit Seoul for talks with his South Korean counterpart, Lee Jong-sup, next week in what could be an occasion to highlight their commitment to cementing the bilateral alliance.

The Chinese fighters entered the Korea Air Defense Identification Zone (KADIZ) at 10:30 a.m. and 11:10 a.m., respectively, from an area southwest of Ieo Islet, a submerged rock south of the southern island of Jeju, and exited it at around noon, according to the Joint Chiefs of Staff (JCS).

One of the fighters reentered the KADIZ at 3 p.m. and left it about 30 minutes later.

Both jets did not violate the South's air space, according to the JCS.

When the two approached the KADIZ, the South Korean Air Force was ready to scramble F-15K combat aircraft and others in a tactical step against a potential accidental situation.

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.