The United States Marine Corps has a further three active divisions and one reserve division. They consist of a headquarters battalion, two or three infantry regiments, an artillery regiment, and a reconnaissance battalion. Additionally, all Marine divisions (MARDIV), except 3rd MARDIV, have an assault amphibian (AA) battalion, a tank battalion, a light armored reconnaissance (LAR) battalion (two in 1st MARDIV), and a combat engineer (CE) battalion (two in 1st MARDIV). (3rd MARDIV has a combat assault battalion including one company each of AA, LAR, and CE. Tank support for 3rd MARDIV can be provided by tanks deployed with the 31st MEU or directly from one of the three divisional tank battalions under the Unit Deployment Program.)