Former President Yoon Suk Yeol was additionally indicted on charges related to the deployment of drones to North Korea last year. 

Yoon, former Defense Minister Kim Yong-hyun and former Defense Counterintelligence Commander Yeo In-hyung were charged Monday with aiding the enemy, power abuse and obstruction of rights.

Kim Yong-dae, the chief of Drone Operations Command, was indicted without detention on charges of obstruction of official duty by hierarchy and soliciting false public documents.

A special counsel team alleges that Yoon ordered drones deployed to North Korea last year in a bid to provoke the North's retaliation and justify his martial law declaration.

The team suspects that military secrets were leaked after the drones crashed in the North.

Some had discussed charging Yoon and the others with inciting foreign aggression through conspiracy with an enemy state, but investigators ultimately applied the general charge of aiding the enemy instead.