South Korean and Australian pilots greet each other as the latter's aerial tanker arrives at an air base in Gimhae, some 310 kilometers southeast of Seoul, to join Freedom Flag, a two-week South Korea-US joint air force drill that began Oct. 21. (Korea Air Force)
South Korean and Australian pilots greet each other as the latter's aerial tanker arrives at an air base in Gimhae, some 310 kilometers southeast of Seoul, to join Freedom Flag, a two-week South Korea-US joint air force drill that began Oct. 21. (Korea Air Force)

South Korea and the United States kicked off a joint large-scale air exercise Thursday, the South's Air Force said, in efforts to bolster their interoperability and combined readiness posture against North Korean threats.

Some 1,100 troops and 90 aircraft from both sides were mobilized for the semiannual Freedom Flag exercise, which runs through May 2, according to the Air Force.

Among the assets mobilized for the two-week drills were the South's F-35A, F-15K and KF-16 fighter jets, as well as the US F-16 and F-35 B fighters and MQ-1 and MQ-9 drones.

Over the next two weeks, troops will take part in key air operations training programs, such as air interdiction, defensive counter air, combat search and rescue and close air support exercises.

For the first time, stealth fighter jets, such as the F-35, will take on the role of "red air" enemy forces to help enhance pilots' practical combat capabilities, the Air Force said.

Freedom Flag was launched last year to replace regular large-scale air exercises between the allies -- Korea Flying Training in the first half of the year and Vigilant Defense in the second half. (Yonhap)