It is sometimes said that one person's ‘freedom fighter’ is another person's ‘terrorist’. This chapter argues that this is not the case: there are well-accepted and clear definitions of terrorism that preclude any such reductive and simplistic equation. After having defined terrorism in a manner generally accepted among serious scholars of the subject, this chapter argues that the just war tradition – often construed as a way of thinking and adjudicating that applies only to collisions between sovereign states – can be usefully applied to conflicts between states and those non-state entities that engage in the planned and intentional destruction of innocents. For, as I have argued elsewhere, just war is not just about war: it is also a way of thinking about politics and political life more generally. Sadly, much political commentary today appears to have lost a robust way in which to speak about politics of which war, in the traditional sense, is a subset. Refusing to think seriously about politics leads to such widely accepted nostrums as those that claim there are ‘root causes’ for terrorism and that unless these are solved or ameliorated, terrorism will flourish. This puts the cart before the horse. It is only after relative political stability, including bringing illegitimate violence to heel, is restored that social questions can be addressed meaningfully. Without a structure of political accountability there can be no meaningful tackling of social questions.