ANKARA

The US and South Korea kicked off an annual large-scale joint military exercise Monday to strengthen their defense readiness against “threats” by North Korea, local media reported.

The 11-day Ulchi Freedom Shield (UFS) exercise, which runs through Aug. 28, include drills to fend off attacks from drones and cyber-attacks, Yonhap News Agency reported.

This year's exercise will mobilize around 18,000 South Korean troops and involve drills incorporating realistic threats aimed at enhancing the two countries’ capabilities across all domains.

While the exercise will be held at a similar scale compared with last year, around half of the initially planned 40 field drills will be rescheduled to September due to concerns like extreme heat and flood damage at some training sites, according to South Korean officials.

North Korea has long characterized the joint exercises as a "rehearsal" for an invasion against it, while the US and South Korea have stressed that the summertime drills are "defensive in nature."

The UFS exercise will be held alongside a four-day civil defense exercise that runs through Thursday, mobilizing about 580,000 civilians.

An anti-air raid civil defense drill will be conducted nationwide on Wednesday as part of the civil defense drills.