Republic of Korea Army Major General Chun Doo-hwan , commander of the Security Command , acting without authorization from Acting President Choi Kyu-ha , ordered the arrest of General Jeong Seung-hwa , ROK Army Chief of Staff , on allegations of involvement in the assassination of President Park Chung Hee . After Jeong 's capture , 29th Regiment of the 9th Division , along with the 1st and 3rd Airborne Brigades , invaded downtown Seoul to support the 30th and 33rd Capital Security Group loyal to Chun , then a series of conflicts broke out in the capital . Two of Jeong 's allies , Major General Jang Tae-wan ( Capital Security commander ) and Major General Jeong Byeong Ju ( special forces commander ) , were also arrested by the rebel troops . Major Kim Oh-rang , Aide-de-camp of Jeong Byeong Ju , was killed during the gun-fight . By the next morning , the Ministry of Defense and Army HQ were all occupied . Chun and his fellow 11th class of Korea Military Academy graduates , such as Major General Roh Tae-woo , commanding general of 9th Infantry Division , and Major General Jeong Ho-yong , were in charge of the Korean military . Chun was supported in the coup and the subsequent consolidation of power by the powerful private club of military officials called Hanahoe
assassination of President Park Chung Hee
Assassination of Park Chung-hee
Coup d'état of December Twelfth