With its combat experience and record in China, the 5th Division was considered one of the best units in the Imperial Japanese Army, and on 12 October 1940, it was placed under the direct control of Imperial General Headquarters and started an intensive training program, including paratrooper exercises in Kyushu together with the 5th Air Group. The division was officially assigned to the Nanshin-ron on 9 November 1941, subordinated to 25th Army (Tomoyuki Yamashita), which was part of the Southern Expeditionary Army Group (Field Marshal Terauchi Hisaichi) based in Saigon.