The M901 is the current main battle tank of the UNSC Army and Marine Corps, and successor to the M808 Scorpion widely used during the Human-Covenant War. The M901 design was first presented to the UNSC by Russian AFV manufacturer Uralvagonzavod in late 2552, as its entry to the newly initiated Primary Armoured Ground Combat Vehicle programme. The M901 design was chosen indefinitely as the successor to the M808 by mid-2553, and Uralgonzavod was contracted for mass production of the vehicle by the end of the year. The M901 main battle tank officially superseded the Scorpion as the UNSC Defence Force's primary MBT on 1 January, 2554.