At the strategic level, a Go program has to manage uncertainty because of the difficulty to correctly evaluate middle game positions (strength of groups, battles). It has to be cautious not to rely on too many uncertain assumptions, otherwise its opponent will find a weakness in the plan. When faced with multiple choices for achieving a given strategic goal, we provide a method for assessing the least hazardous plan (a plan is a subtree of goals that leads to the success of the root goal). We combine AND/OR tree search with probability estimations of success of the achievement of the goal. Intuitively, errors cumulate at AND nodes because different conditions have to be satisfied at the same time.