Prosecution officials arrest Cho Hyun-chun (at the center), a former head of the now-defunct Defense Security Command, at Incheon International Airport, west of Seoul, on Wednesday. (Yonhap)

Prosecutors arrested Cho Hyun-chun, a former head of the now-defunct Defense Security Command, upon his arrival in South Korea on Wednesday, more than five years after he fled to the United States over suspected masterminding of a martial law plan.

Officials from the Seoul Western District Prosecutors Office apprehended the 64-year-old former commander at Incheon International Airport and transferred him to the office for investigation.

Cho allegedly instructed a task force he formed in February 2017 to draw up a contingency plan based on an illegal declaration of martial law to crack down on candlelight protesters by force and reported it to the then Defense Minister Han Min-koo.

Months of street candlelight vigils by many people led to the impeachment of then President Park Geun-hye at the time.

After retiring in September 2017, Cho fled to the US three months later amid a widening probe into the case.

"I came back to help reveal the truth behind the martial law document as the person responsible for it and take responsibility if I have any," Cho told reporters at the airport. (Yonhap)