The Swedish Armed Forces are evolving from a traditional invasion-based defence towards a flexible effort based defence, which will require significantly improved situational awareness and the ability to perform high-precision operations. Robust positioning will be of utmost importance in order to accomplish this. The future command and control system will consist of numerous sub-systems and common time will be essential to synchronize communication systems and operations. One possibility to obtain position and time information is to use GNSS (Global Navigation Satellite Systems) e.g. GPS, GLONASS, and in the future, GALILEO. All GNSS are extremely sensitive to interference and a key technique to protect them is antenna arrays and adaptive beamforming. A qualified attacker will employ anti-jam techniques to their GNSS receivers to perform precision operations and therefore methods and techniques to jam such systems must be developed. A less qualified antagonist may use GNSS jammers and consequently anti-jam GNSS receivers should be used. This report describes the project "Navigation Warfare" and the activities performed during 2004, which can be summarized as follows: 1) Development of methods for jamming anti-jam GNSS. 2) Demonstrator. 3) Development of simulation environment. 4) Information gathering - knowledge build up - dissemination of results. 5) Contacts and reports.