The Uncontrollable Momentum of War

By RORY STEWART
Published: September 9, 2011

The initial decision to strike back after the 9/11 attacks is easy to understand. History, however, will ask not why the West invaded Afghanistan, but why did it stay so long?

Why, a decade after 9/11, were there still 140,000 coalition troops on the ground? Why were there so many civilian casualties in May and June 2011 — more than in any preceding recorded month? Why had the United States been in Afghanistan for twice the length of World War II?

The conventional answer to all these questions is that Afghanistan still poses an existential threat to global security. In March 2009, presenting his strategy for a surge in troop numbers, President Obama said, “If the Afghan government falls to the Taliban ... that country will again be a base for terrorists who want to kill as many of our people as they possibly can.â€