There is now a major new interest in ethical issues about warfare emerging from the wars in Iraq and Afghanistan, conflict in Syria and Libya, the war on terror, and the introduction of new weapon systems, such as unmanned drones. In this re-written version of the author's classic text, Waging War, Ian Clark asks probing questions about how we think about war, the changes it is undergoing, and what exactly it is we wage when we wage war. Waging War argues that much of what passes for ethical debate is actually a set of disagreements about what counts as war or not. This philosophical introduction provides a critical review of the various different ways in which the ethical debates are already framed, the questions that arise from these debates, and seeks to bring greater clarity and precision to the important moral arguments about political violence.