International engagement is as old as the existence of mankind on the surface of planet earth. The complexity of cosmos intercourse increases and changes with respect to the development of human society, which is a response to discovery, innovation in science and technology. Prior to the Westphalia treaty of 1648, monarchs and individuals were the dominant actors in global interaction (Odo, 2012). They were faced with some unique impediments in turn with time, environmental factors and likewise, vis-à-vis mechanisms for mitigation. With the birth of the modern state system, the state has taken a prominent position in shaping the international fora (Shehu & Garba, 2020). Scholarship and scholars' postulation about how, where, what, when and why of international relations is a contextual phenomenon. The scope of international relations is as wide as the challenges therein: general and specific. One of such is strategic thinking and within is international law and law war. Security studies is a component of international relations of mainstream political science. During the 40 years period that followed the Second World War, between 1945 and 1985, there have been more than 140 wars and armed conflicts. In the same epoch, armed conflict and war broke out on the territory of 69 countries with the participation of 81 states (Tunkin, 1986). In other sense, Nigeria state was geographically European during the 1884/1885 Berlin conference. Nigeria got her independence on 1st October 1960 from a British colonial lord. Since then Nigeria has not gone to war with any state but is fighting various internal crises. Among such is Boko Haram insurgency which came limelight in the year 2002 (Shehu, 2021). The movement is seeking to replace democratic institutions of government with Islamic oriented via jihad. The general thrust of this research is to examine historical development that midwife principles of jus ad bellum. While the specific are: to examine international law and jus ad bellum; to identify conventions and scholars on the jus ad bellum; and to identify and apply the principles of jus ad bellum in Nigeria respond to Boko Haram. Manuscript profile