Of all the major powers in contemporary international politics, this chapter suggests, Russia’s national security policy has appeared the most unstable, traversing a trajectory from an initial pro-Western orientation after the Soviet collapse to a strategy of multipolarism where cooperation with the West has been conditional. More recently, its national security posture has often been that of a bellicose and muscular ‘spoiler’ defined by a willingness to use military force, offensive cyber weapons and information warfare, hybrid capabilities, espionage and sabotage. The chapter addresses two key questions here: why has Russian national security policy followed this path; and what have been the major factors that have driven Russia’s turn towards its current posture? To answer these questions, the chapter explores the sources of Russian national security policy, its main rationales, and the constraints and limitations on Russian choices in future. In doing so it makes an argument that some readers may find surprising or confronting: that even though its methods have become much more assertive over time, there has actually been remarkable consistency in Russian national interests since the Soviet collapse.