text: Chapter 9
  or fragmentary order. The BCT commander, with the support of the staff and upon the advice of the BSB
  commander determines the control exercised by the BSB commander in governing the authority and
  limitations of the BSB to execute area security within the BSA. Considerations used in determining the
  authority and limitations of the BSB commander to execute area security within the BSA are—threat levels
  and situation; utility of different locations; and civil considerations.
  LOCATIONS FOR SUPPORT AREAS
  9-180. The BSB commander, in coordination with the BCT S-3 and S-4, recommends to the BCT
  commander the layout of the BSA. The BSB commander coordinates land usage with the overall support
  area’s terrain manager, typically the BEB commander. Support areas are located so that support to the BCT
  can be maintained but does not interfere with the tactical movement of BCT units or with units that must pass
  through the BCT area, while still maximizing security. The BSA’s size varies with terrain and number of
  sustainment units. Usually the BSA is on a main supply route and ideally out of the range of the enemy’s
  indirect-fire artillery. Position the BSA away from the enemy’s likely avenues of approach and entry points
  into the BCT’s main battle area (MBA).
  9-181. In determining the location for the BSA, there is a constant balancing of supportand security, which
  ultimately determines the best placement of support areas. The BSB commander balances constant support
  operations and security requirements for the BSB as it establishes and operates the BSA. The BSB
  commander integrates both activities to not degrade the BCT’s combat effectiveness. The BSB commander
  ensures logistics missions and associated activities continue without restriction and that all units within or
  transiting the support area are capable of conducting self-protection against alevel I threat.
  9-182. Threats in the BCT and higher echelon support areas are categorized by the three levels of defense
  required to counter them. Any or all threat levels may exist simultaneously in these support areas. Emphasis
  on defense and security measures depends on the anticipated threat level. A level I threatis a small enemy
  force that can be defeated by those units normally operating in the echelon support area or by the perimeter
  defenses established by friendly bases and base clusters (ATP 3-91). A level I threat for an echelon support
  area or base camp consists of a squad-sized unit or smaller groups of enemy soldiers, agents, or terrorists.
  Typical objectives for a level I threat include supplying themselves from friendly supply stocks; disrupting
  friendly command and control nodes and logistics areas; andinterdicting friendly lines of communication.
  9-183. A level II threat is an enemy force or activities that can be defeated by a base or base cluster’s
  defensive capabilities when augmented by a response force (ATP 3-91). A typical response force is a military
  police platoon (with appropriate supporting fires) for an echelon support area or base camp; however, it can
  be a combined arms maneuver element. Level II threats consist of enemy special operations teams, long-range
  reconnaissance units, mounted or dismounted combat reconnaissance teams, and partially attrited small
  combat units. Typical objectives for a level II threat include the destruction, as well as the disruption, of
  friendly command and control nodes and logistics and commercial facilities, and the interdiction of friendly
  lines of communications.
  9-184. Alevel III threatis an enemy force or activities beyond the defensive capability of both the base and
  base cluster and any local reserve or response force (ATP 3-91). It consists of mobile enemy combat forces.
  Possible objectives for a level III threat include seizing key terrain, interfering with the movement and
  commitment of reserves and artillery, and destroying friendly combat forces. Its objectives could also include
  destroying friendly sustainment facilities, supply points, CP facilities, airfields, aviation assembly areas,
  arming and refueling points, and interdicting lines of communications and major supply routes. The response
  (usually task organized at the division or corps level) to a level III threat is a tactical combat force,a rapidly
  deployable, air-ground, mobile combat unit with appropriate combat support and combat service support
  assets assigned to, and capable of, defeating level III threats, including combined arms (JP 3-10). (See
  ATP3-91 for additional information.)
  9-185. Once positioned, units should not consider echelon support areas such as the trains or BSA as
  permanent or stationary. Support areas (specifically echeloned trains) must be mobile to support the units
  when they move and should change locations frequently depending on available time and terrain. A change
  of location may occur with a change of mission or change in a unit’s area of operations. Movement to a new
  location may be required to avoid detection caused by heavy use or traffic in the area or an area becomes