In 1931, Japan attacked China and occupied Manchuria and created the puppet-state of Manchukuo. The Japanese offered Garmaev to recruit Buryat-Mongolian troops. He agreed and the Manchukuo War Department appointed him as a Commander of Northern Xing'an Security Forces (興安北省警備軍司令官) with a rank of major general. His troops were guarding the border with the Soviet Union and the Mongolian People's Republic.