A policy was a set of rules or principles that guided a government or organization in making decisions and taking action.
While being asked by Captain Jean-Luc Picard, "Based on your analysis, what is the current Romulan strategy behind the deployment of their ships in this sector?", Data replied, "Their ships are deployed to support a policy of confrontation designed to test Federation defenses along the Neutral Zone." (TNG: "Data's Day")