SEOUL (AFP) — South Korean prosecutors indicted former President Yoon Suk Yeol on Monday on new charges of aiding the enemy, alleging that he ordered drone flights over North Korea to strengthen his effort to declare martial law.

North Korea said last year it had “proved” that the South flew drones to drop propaganda leaflets over its capital Pyongyang, an act that Seoul’s military has not confirmed.

State prosecutors opened a special investigation this year to examine whether sending the drones was an illegal attempt by Yoon to provoke the North and use its reaction as a pretext for declaring military rule.

Prosecutor Park Ji-young told reporters on Monday that the special counsel team had “filed charges of benefiting the enemy in general and of abuse of power” against the former president.

Yoon and others “conspired to create conditions that would allow the declaration of emergency martial law, thereby increasing the risk of inter-Korean armed confrontation and harming public military interests,” said Park.

She added that compelling evidence had been found in a memo written by Yoon’s former counter-intelligence commander in October last year, which pushed to “create an unstable situation or seize an arising opportunity.”

The memo said the military should target places “that must make them (the North) lose face so that a response is inevitable, such as Pyongyang” or the major coastal city of Wonsan.

Seoul and Pyongyang have remained technically at war since the 1950-53 Korean War ended in an armistice, not a peace treaty.

Yoon plunged South Korea into political crisis when he sought to subvert civilian rule in December last year, sending armed soldiers to parliament in a bid to stop lawmakers voting down his martial law declaration.

The effort failed, and Yoon was eventually detained in a dawn raid in January, becoming South Korea’s first sitting president to be taken into custody.

He was removed from office in April, and voters replaced him with Lee Jae Myung in a general election in June.

Yoon remains on trial for insurrection and other offenses linked to his declaration of martial law.