The Seoul Central District Court found Yoon guilty of abuse of power and aiding the enemy, saying he had conspired in the October 2024 drone incursion from the outset, the news agency said.
Yoon denied wrongdoing. His lawyers said he neither ordered nor later approved the operation, which they said was unrelated to martial law and instead a response to months of launches by the DPRK across the border of balloons stuffed with rubbish.
Prosecutors had sought a 30-year prison term for Yoon in April.
The ruling adds to a series of judgements against the ousted conservative leader, once South Korea’s top prosecutor, whose martial law order plunged Asia’s fourth-largest economy into its deepest political turmoil in decades.
In February, a South Korean court sentenced Yoon to life in prison after finding him guilty of leading an insurrection linked to the martial law attempt.
He was removed from office last year after the Constitutional Court upheld his impeachment, triggering a snap election that was won by liberal President Lee Jae Myung.
Yoon, who is already in custody, can appeal against Friday’s lower court ruling. (Reuters)
