In commemorations across the country this month, millions of Americans reflected on the devastating attacks of Sept. 11, 2001 — the incalculable loss of life, energy and talent; the courage of the passengers and crew aboard the doomed jetliners; and the gritty determination of the brave rescue workers who rushed into harm’s way. We also thought about the sacrifices that we have asked the men and women in our nation’s military and intelligence services to make — sacrifices that led to the killing of Osama bin Laden, and which have seriously degraded al Qaeda’s ability to attack us with that level of ruthlessness again.