As the US military presence in South Vietnam grew, MACV quickly outgrew these quarters and on 2 July 1966 construction of a new purpose-built facility () adjacent to Tan Son Nhut Airport and the ARVN Joint General Staff Compound was commenced. Due to the size of this facility, the new headquarters were labelled Pentagon East. The building was designed and constructed under the supervision of the U.S. Navy Officer in Charge of Construction RVN. The construction contractor was RMK-BRJ at a cost of $28 million.