A joint task force (JTF) is established when the scope, complexity, or other factors of the contingency or crisis require capabilities of Services from at least two Military Departments operating under a single joint force commander (JFC). The JTF establishing authority designates the commander, joint task force (CJTF), assigns the mission, designates forces, delegates command authorities and relationships, and provides other command and control (C2) guidance necessary for the CJTF to form the joint force and begin operations. The appropriate authority may establish a JTF on a geographic or functional basis or a combination of the two. In either case, the establishing authority typically assigns a joint operations area (JOA) to the JTF. The size, composition, capabilities, and other attributes will vary significantly among JTFs based on the mission and various factors of the operational environment, such as the adversary, the geography of the JOA, the nature of the crisis (e.g., flood, earthquake), and the time available to accomplish the mission.