To avoid being detected by enemy electronic surveillance units, radio silence is an important ability of military communication networks. We give a short overview of the problems caused by using radio silence in multi-hop networks and discuss mechanisms that are required for efficient use of radio silence in tactical scenarios. The use of radio silence in multi-hop networks are more difficult than in single-hop networks, due to the need for more internal network information. Different techniques have different pros and cons, and we compare two main techniques for military ad hoc networks from a radio silence perspective. Finally, a number of properties of ad hoc-networks which would allow a network to leave radio silence almost immediately are suggested.