A navigation function based path planner is developed in this paper for the navigation of multiple unmanned aerial vehicles (UAVs) in the presence of known stationary obstacles and unknown enemy assets (EAs). Specifically, the motion of UAVs are planned in a centralized fashion. The standard navigation function approach is extended to a multiple navigation strategy with an analytical switch among different cases due to the limited sensing zone of the UAVs. A differentiable controller is proposed based on this navigation function that yields asymptotic convergence. A discussion for avoiding moving EAs is presented.