To be successful, grand strategy requires objectives, concepts, and resources to be balanced appropriately with a view to defeating one's enemy. The trouble is, of course, that Generals are always well prepared to fight the last war. In the words of Yogi Berra, predictions are always difficult, especially when they involve the future. Yet, grand strategy is all about the future. But how is one to strategize about a future that is inherently difficult to predict? One way to overcome this conundrum is to rely on independent variables that can be projected into the future with reasonable accuracy. Aside from environmental indicators, the most consistent of those is demography, specifically demographic change and difference. The demographic approach to international security leads to strategic conclusions about the integration of military, political, and economic means in pursuit of states' ultimate objectives in the international system.
Leuprecht, C. (2010). International Security Strategy and Global Population Aging. Journal of Strategic Security, 3(4), 27–48. https://doi.org/10.5038/1944-04220.127.116.11