As noted by University of North Carolina at Chapel Hill professor Richard H. Kohn, "civilian control is not a fact but a process". Affirmations of respect for the values of civilian control notwithstanding, the actual level of control sought or achieved by the civilian leadership may vary greatly in practice, from a statement of broad policy goals that military commanders are expected to translate into operational plans, to the direct selection of specific targets for attack on the part of governing politicians. National Leaders with limited experience in military matters often have little choice but to rely on the advice of professional military commanders trained in the art and science of warfare to inform the limits of policy; in such cases, the military establishment may enter the bureaucratic arena to advocate for or against a particular course of action, shaping the policy-making process and blurring any clear cut lines of civilian control.