The present invention relates to planning of a trajectory for minimum threat exposure in a given geographical region. A trajectory is planned from a start node to a final node in a digital representation of the geographical region. The threat exposure for a vehicle moving along the trajectory is determined. Navigation performance of the vehicle along the trajectory is evaluated. A rate of survival based on threat exposure and navigation performance along the trajectory is estimated. A new trajectory is planned from the start node to the final node until a best rate of survival is established for the planned trajectory.