 Having pushed back U.S. forces at Osan , Pyongtaek , and Chonan , the North Korean 4th Infantry Division , supported by elements of the 105th Armored Division , continued its advance down the Osan — Chonan road , up to 12 @,@ 000 men strong under division commander Lee Kwon Mu in two infantry regiments supported by dozens of tanks . Behind it , the North Korean 3rd Infantry Division had yet to engage the American forces . 
