Atlantic Council

9/11 was the defining event of the new millennium, but not for the reasons we thought for most of the ensuing decade. For most of that period we would have pointed to 9/11 as the beginning of twenty-first century warfare: perpetual vigilance and probing pre-emptive strikes against an ill-defined, global, networked and largely non-state enemy. From the vantage point of 2011, however, it is far more likely that historians will see 9/11 as the catalyst for the end of twentieth-century warfare: large-scale, multi-year deployments requiring the conquest, control and long-term stabilisation and reconstruction of foreign territory. The nuclear weapons that ended the Second World War ended great power war. The fall of the Soviet Union ended great power proxy war among current great powers, although Pakistan certainly thinks it is fighting India in the valleys and cities of Afghanistan. The second Iraq war and the war in Afghanistan are ending boots-on-the ground wars of counter-insurgency and regime change.

The great power wars of the twenty-first century will be fought by special forces: specialised in combat against pirates, terrorists and global criminal networks; in focused search and rescue and search and destroy missions; and in civilian protection units capable of disabling but not destroying an enemy. They will be fought by cyber-warriors, skilled in manipulating unmanned weapons and in deterring and responding to system-wide cyber-attacks. And they will be fought in multilateral coalitions aimed at stopping the wars that criminal governments wage against their own people and bringing individual leaders and their coterie of high-level supporters to justice.

Many readers will shake their heads and think how short is historical memory. 'Never again' has as little impact on the decisions to mobilise armies as it does on the decisions to stop genocide. Reasons always exist to send in the troops; it is just that war-weary, broke, frustrated Americans confronted with their crumbling domestic human and physical infrastructure have temporarily forgotten or forsworn them. Perhaps. But as two American military officers argue compellingly in a twenty-first­ century sequel to George Kennan's 'Long Telegram' (the X article), the world's greatest military power, near the height of its military dominance, is confronting a world in which control is giving way to credible influence (Mr Y, 'A National Strategic Narrative', 2011). No country, however mighty, can direct or determine global outcomes (it never could, but the illusion was good enough for government work). The best it can hope reflections on the 9/11 decade for is to influence others - governments and societies alike - in shaping events and adapting to a continuous stream of changing challenges. In this world we will not 'win wars'. We will have an assortment of civilian and military tools to increase our chances of turning looming bad outcomes into good - or at least better - outcomes.

The horrific attacks on that brilliant blue September morning brought down not only buildings and planes, but also Americans' towering certainty that they could go about their daily lives without fear of enemy attack. A decade later, we are learning to face and even embrace an age of perpetual uncertainty. But it was the US responses to 9/11 - actual (Afghanistan) and purported (Iraq) - that brought the lesson home. Twentieth-century means are no match for twenty-­first-century problems.

Anne-Marie Slaughter, an Atlantic Council Board member, is Dean of the Woodrow Wilson School of Public and International Affairs and the Bert G. Kerstetter '66 University Professor of Politics and International Affairs at Princeton University. This article was originally published in The RUSI Journal.