South Korea and the United States on Thursday were set to conclude a major summertime combined exercise held in a scaled-back manner due to the coronavirus situation and peace efforts involving North Korea, officials said.

The nine-day computer-simulated Combined Command Post Training began on Aug. 16, mobilizing the minimum level of troops without any outdoor drills, according to the Joint Chiefs of Staff (JCS).

This year's summertime exercise kicked off amid strong protests from North Korea, with Kim Yo-jong, the sister of North Korean leader Kim Jong-un, blasting the drills as an "unwelcoming act of self-destruction for which a dear price should be paid."

North Korea has been refusing to answer the South's regular phone calls via liaison and military hotlines since Aug. 10, when South Korea and the US launched a preliminary exercise in the run-up to the main training.

Pyongyang has long railed against such exercises, denouncing them as a rehearsal for invasion, though Seoul and Washington have stressed that they are regular ones that are purely defensive in nature.

During the main exercise, the two sides were again unable to carry out a Full Operational Capability (FOC) test, further dimming prospects for Seoul's retaking of the wartime operational control (OPCON) of its troops from Washington at an early date.

An FOC test is a crucial step to check if South Korea is on course to meet conditions required for retaking the OPCON, which has no specific deadline.

It was supposed to be held last year as part of the allies' combined training, but the two countries failed to do so due to the COVID-19 situation.

Officials said some of the drills this year were conducted under FOC conditions "to maintain the progress on the conditions-based" OPCON transition. (Yonhap)