Seoul, Aug 20 (IANS): South Korea and the US are set to kick off major combined military drills this week as the allies seek to bolster joint readiness against evolving military threats from North Korea.

The annual Ulchi Freedom Shield (UFS) exercise, based on an all-out war scenario, is set to take place from Monday to August 31, featuring various contingency drills, such as the computer simulation-based command post exercise, concurrent field training and Ulchi civil defence drills, Yonhap news agency reported.

Some 30 allied field training events are scheduled to take place during the exercise period, compared with 25 during this year's springtime Freedom Shield exercise and 13 in last year's UFS, according to a Joint Chiefs of Staff (JCS) official.

This year's UFS is known to include scenarios to train troops to swiftly transition into wartime as well as to respond to false information possibly spread by Pyongyang during wartime or a contingency.

In addition to the allies' Army, Navy, Air Force and Marine personnel, US space forces will also partake in the drills, according to the US Forces Korea (USFK).

The US military launched the US Space Forces Korea, a USFK component, in December last year.

Aside from South Korean and US participants, personnel from nine member countries of the UN Command (UNC) will join the exercise. The countries are the UK, Australia, Canada, France, Greece, Italy, New Zealand, the Philippines and Thailand, according to the USFK.

The UNC is a key enforcer of the armistice that halted the fighting in the 1950-53 Korean War.

The Neutral Nations Supervisory Commission, an observer of the armistice, will also attend the drills. The commission has representatives from Sweden and Switzerland.

Meanwhile, the South Korean military is strengthening its readiness posture against possible military activities by Pyongyang during the exercise period, such as ballistic missile launches.

The North has long accused the allies' military drills of being rehearsals for an invasion against it, with North Korean leader Kim Jong-un recently calling for a "drastic boost" in the country's missile production capability and for war contingency preparations in an "offensive" manner.

Seoul's spy agency told lawmakers Thursday during a closed-door briefing that the North is preparing various provocations in time for the combined drills, such as an intercontinental ballistic missile launch.