World War Aid offers a novel perspective on the unprecedented aid in the Ukrainian conflict, destined to leave an international "echo" reaching far beyond the individual historical case and the aid sector alone. This book clarifies the evolving scenario of a conflict that, before tanks, had long been fought on the territory of aid. The author makes arguments about aid which can be traced back to three sets of issues: 1) Ukraine’s history from its independence in 1991 until the war in 2022, that witnessed the evolution of inter-state aid sent to Kyiv. This period anticipated the geo-political dispute over the country's future, and was marked by confrontation between donors who would later become the protagonists of the war scenario. 2) The exceptionality of the Ukrainian case is discussed by specifically identifying eight peculiarities of wartime aid: the response speed of Western Bilateral Donors; the leading role and primacy of the latter over the non-governmental sector; the key influence exercised by the Ukrainian recipient; the quantity and diversification of aid involved; Russia’s conversion of aid into hybrid weapons (Weaponization of Aid); the West’s provision of weapons as primary aid (Aidization of Weapons); the excessive anticipation of post-war planning initiatives; and sanctions modeled to represent a new form of aid. 3) Based on these peculiarities, a new model of Interventionist Aid is defined, characterized by a willingness to take an active part in the crisis in which the Donors operate, in order to condition its course and outcome. By preferring tactical purposes to humanitarian ones, and prioritizing military and financial interventions, Interventionist Aid represents an absolute conceptual, political and historical novelty in inter-state aid. A highly original take on a key event of the 21st century, World War Aid is an invaluable text for political scientists, analysts and historians of international relations, as well as diplomats and practitioners of foreign policy and foreign aid.