Tactical military communication networks operate in highly complex environments. The survivability and the range of these networks, especially the mobile wireless segments, are and will be a challenge for the present and future defence forces. OPAL, an autonomous system, has been previously presented where it extended the range and improved the survivability of tactical military networks using unmanned aerial vehicles (UAVs). In this paper, we extend that system to operate in a contested electromagnetic environment caused by jammers. OPAL is shown through emulation to be robust in maintaining effective communications between the nodes in such a scenario.