"vertical envelopment" (i.e., air assault) operations when supported by MV-22 medium tiltrotor and/or CH-53 heavy helicopters and mechanized operations (when supported by attached amphibious assault vehicle units). Additionally, some Marine infantrymen (usually only those assigned to reconnaissance or special operations units) attend U.S. Army Airborne or Ranger training. However, since the USMC does not maintain either airborne or Ranger infantry units, only a relatively small number of Marines ever attend these two schools. Furthermore, while not designated as special operations forces, deployed Marine Expeditionary Units (containing a heavily reinforced Marine infantry battalion, consisting of approximately 1,200 Marines and Navy personnel, designated as a BLT) are certified as capable of performing some ""special operations"" type missions. In addition to significant differences between Marine infantry and their US Army counterparts in training and organization, there are some differences in individual weapons, equipment, and vehicles, as well. The Marine Corps conducts infantry training at three locations: The Basic School, Marine Corps Base Quantico, VA (for officers) School of Infantry (East), Camp Lejeune, NC (for enlisted Marines) School of Infantry (West), Camp Pendleton, CA (for enlisted Marines) Current Marine Infantry Organization 1st Marine Division (3 Marine infantry regiments containing 9 Marine infantry battalions) 2nd Marine Division (3 Marine infantry regiments containing 9 Marine infantry battalions) 3rd Marine Division (2 Marine infantry regiments containing 6 Marine infantry battalions) 4th Marine Division (2 Marine infantry regiments containing 8 Marine infantry battalions) Organization The size of the GCE varies in proportion to the size of the MAGTF. A Marine Expeditionary Force has a division (MARDIV). A Marine Expeditionary Brigade holds an infantry regiment, reinforced with equipment and personnel from various divisional combat support regiments (i.e., artillery) and battalions (e.g., armor). The various Marine Expeditionary Units command a reinforced infantry battalion, which includes various combat support unit attachments. Generally, MEF postings are permanent, while MEBs and MEUs rotate their GCE, ACE, and LCE twice annually. Hierarchy of Marine ground units 1st Marine Division 1st Marine Regiment 5th Marine Regiment 7th Marine Regiment 11th Marine Regiment Other 1st Marine Division battalions 2nd Marine Division 2nd Marine Regiment 6th Marine Regiment 10th Marine Regiment Other 2nd Marine Division battalions 3rd Marine Division 3rd Marine Regiment 4th Marine Regiment 12th Marine Regiment Other 3rd Marine Division battalions 4th Marine Division 14th Marine Regiment 23rd Marine Regiment 25th Marine Regiment Other 4th Marine Division battalions See also Air Naval Gunfire Liaison Company