South Korea's special counsel investigating former president Yoon Suk-yeol's alleged attempt to declare martial law conducted raids on Monday at the Drone Operations Command (DOC) and the Ministry of Defense, signaling that the insurrection investigation has escalated to potentially include treason charges, Yonhap News reported on Monday.

Yoon is currently on trial for insurrection charges in connection with his failed martial law attempt. Media reports suggest he may have instructed senior military officials to deploy drones to the Democratic People's Republic of Korea (DPRK) last year as part of his broader martial law strategy, according to the news agency.

"The special counsel suspects that Yoon ordered the military to send the drones to Pyongyang last October to provoke North Korea and use it as justification for imposing the December 3 martial law, which was blocked by a National Assembly vote only a few hours later," it added.