 It's clear that the deficit crisis requires all of our government functions to reduce their planned spending levels, and defense will be no exception. It's not plausible, programmatically or politically, to exclude the 20 percent of government spending that's encompassed by the defense function from deficit reduction plans. So the challenge we face today is to manage the coming slowdown in defense spending wisely and responsibly. This requires making judgments about the nature of our future security environment, which is an exceptionally tricky business. I'd identify three strategic trends that could shape our future national security environment – lethality, duration, and asymmetry. Each of these trends has implications for how we design our defense programs going forward. Each, if not carefully managed, could weaken our security. The first and most prominent trend in the global strategic environment has to do with access to lethality. Our military must be able to confront both high-end and low-end threats. We must have what Secretary Gates called a portfolio of capabilities with maximum possible versatility across the widest spectrum of conflict. The increase in lethality across the threat spectrum means we cannot prepare exclusively for either a high-end conflict with a potential near-peer competitor or a lower-end conflict with a counterinsurgency focus. The second strategic trend is the increasing duration of warfare. For several decades of military planning, we have assumed kinetic engagements would be relatively short. And that is how we plan for intense but ultimately short battles that yield a decisive victory. Because duration becomes as important a driver of planning as intensity, we must maintain enough force structure to allow adequate dwell times between deployments. This is likely to have important implications for how we size, structure, and utilize our reserve force components. We need the ability to scale up force structure for longer conflicts. And the long-term conflicts must be considered in our strategic calculus. The third final trend in war is the increasing prevalence of asymmetric threats. Battlegrounds used to be a meeting place of like-on-like forces, cavalry on cavalry, armor on armor, and in the Cold War, nuclear against nuclear. We generally faced enemies whose framework for the use of force was similar to our own. Our challenge was to develop superior capabilities and tactics within that framework. This like-on-like paradigm is disappearing. In stature, the American military is dominant by almost any measure. There are very few militaries that can or will challenge us directly. Yet we are finding that very dominance causes our adversaries to become more creative in their approach. Just as World War I showed the obsolescence of cavalry and World War II the battleship, we may be surprised at how rapidly our current state-of-the-art systems are overcome by developments that we cannot foresee today. But I also believe that we can make informed judgments about the future of war by looking beyond specific scenarios to the underlying trends of warfare and the historical forces that drive them.