1. A method of planning a trajectory for minimum threat exposure in a given geographical region wherein the trajectory is planned from a first node to a second node in a digital representation of the geographical region, comprising: i) selecting a trajectory from the first node to the second node ii) determining threat exposure for a vehicle moving on a trajectory from the first node to the second node; iii) evaluating navigation performance for the vehicle moving along the trajectory iv) estimating a rate of survival based on threat exposure and navigation performance along the trajectory v) repeating steps i)-iv) until a trajectory with a best rate of survival is selected.