Aroadside bomb in Baghdad on Sunday pushed U.S. casualties in Iraq to 4,000, prompting President Bush's avowed promise for "an outcome that will merit the sacrifice" of those killed. Mr. Bush's sentiment, while predictable for a commander in chief, offers no more assurance than a wish and a prayer. Mr. Bush has little ability to bring this ill-gotten war to a positive end. He is resolved to seeing the battle through, despite the war's unpopularity, the military's increasing fatigue and the Iraq government's inability to go it alone.

Nevertheless, the death toll of American service men and women remains a source of commentary and dismay. It's as though, with the number of fatalities now at 4,000, some threshold has been crossed. What does the number represent? A shift in the course of the war, an acceleration of violence, an anticipation that more will fall?

The fact that 4,000 U.S. troops have died in this ghastly war suggests none of that. But it reinforces starkly, the grave consequences of the Bush administration's bravado in going to war five years ago without sufficient military strength, a post-war plan or an exit strategy.

This accounting should in no way diminish the individual loss that every soldier's death presents: the absent father or mother, the widowed spouse, the parentless child and grieving parent. The four servicemen killed Sunday are not yet known to us, but they are the latest to follow Marine Staff Sgt. Kendall D. Waters-Bey, 29, of Baltimore; Marine Cpl. Nicholas Lee Ziolkowski, 22, of Towson; Army Spc. Toccara R. Green, 23, of Rosedale; Army Pfc. Amy Duerksen, 19, of Aberdeen; Marine Maj. Douglas A. Zembiec, 34, of Severna Park; Army Spc. Micheal B. Matlock Jr., 21, of Glen Burnie; and the 3,990 other soldiers, airmen and seamen who have lost their lives since 2003.

Four thousand dead. Many more Americans fell in the Battle of Iwo Jima in 1945 and during the 1968 Tet Offensive in Vietnam, and yet the unpopularity of this war, the futility of the mission, the uncertainty over its end keep the casualties in the headlines. Four thousand dead, the enormity of the loss rests in this image: Their coffins, resting head to toe, would stretch five miles.