5-45. Threats in the division support area are categorized by the three levels of defense required to counter them. Any or all threat levels may exist simultaneously in the division support area. Emphasis on base defense and security measures may depend on the anticipated threat level. A Level I threat is 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 a typical base 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 mission command nodes and logistics facilities; and interdicting friendly lines of communication.