Defence and Security (DAS) is an interdisciplinary subject, the totality of which aims to generate an understanding of how best to employ the military as an instrument of power within the international system. This broad and eclectic field can be divided into several areas. The first is international politics and, in particular, theories of international relations that talk specifically to the problem of war and conflict, for example, the school of Realism and related to this field of geopolitics. An established subfield within this discipline of international relations is strategic studies, which focuses almost exclusively on the use of military power. Within this context, we are interested in understanding the causes of conflict and instability, which are wide-ranging and how, in a theoretical sense, military power can be used to prevent war through various strategies based on the concept of deterrence.
We also recognise that the concept of security has changed dramatically and is no longer concerned solely with defence as in the past. This contested concept is applied ever more widely to a range of actors and policies, and this too, has driven and shaped the debate in the wider area of the DAS domain. As a result, the vista of the discipline has expanded to include a range of areas that, in the past, sat separately from defence. Today, the discipline explores how economics, culture and politics feed into the conflict spectrum. Of particular importance here is the increasing importance of non-traditional security challenges in the form of pandemics, demographics, migration and climate change and how this feeds back into the conflict spectrum in the form of terrorism, insurgency and interstate wars.
The second principal area of research explores how states respond to these challenges, which takes us into the realm of the policy-making process employed by states and the pursuit of optimal solutions that ensure they achieve the greatest level of security at the lowest possible cost. As a result, we also draw on political theory to help us understand how and why the security architectures of the state have evolved in the way they have.
The third intellectual strand of DAS focuses on how states use power to achieve greater security in peace and war. Here the main line of inquiry is on strategy. At its highest level, we are most interested in grand strategy, which combines military and other forms of power to coordinate their activities in prosecuting a single goal designated by the national government. The second focuses on the application of military strategy and how military and other forms of power are employed in the active prosecution of a political objective. During peacetime, this can be in the form of discussion about deterrence, and, if that fails, the application of strategy during the conduct of war. This vital element of DAS draws heavily on military history and strategic theory to allow a critical light to be shed on the conduct of recent wars and how military power can be used both to prevent and expedite the timely and efficient use of force.
In sum, Vegetius observed: `If you want peace, prepare for war.' This is the starting point for those who work and research in this interdisciplinary area. Their purpose is to understand the causes of contemporary conflict, how best military and other forms of power can be used to prevent or limit the outbreak of war and, if war should happen, how best to ensure it is employed quickly and decisively. Underlying this is a belief and conviction that military power should be carefully calibrated so that it supports rather than undermines the achievement of the political goal. Understanding this last point is often the most problematic issue facing governments when deciding how and when to use force to support their international objectives and obligations. DAS provides an insight into how difficult this is and, in theory, offers solutions about how best to avoid making the same mistakes as previous governments and states have done in the past.