"If the public really believed that our war in Iraq now was about stopping aggression, stopping terrorism, then we would see a greater degree of tolerance for casualties," says Bruce Jentleson, a former policy planner in President Clinton's State Department who now teaches at Duke University.

Nancy Lessin, co-founder of the antiwar group Military Families Speak Out, says many people appear to believe that "one death is too many in a war that should never have happened."

At the same time, scholars suggest that America's instant technologies and its global power have conditioned its population to expect quick, painless results in almost any war.

"In a world of smart bombs and so on, you just expect the military to be able to insulate the military from getting killed — and to a large extent they have," says Christopher Gelpi, a casualty researcher at Duke University.

Precision air power helped the U.S. military succeed in the former Yugoslavia and the first war with Iraq, and scholars say that lowered the expectation of casualties in future wars. Improvements in body armor may have contributed to the same expectation.

Speed-of-light consumer conveniences, like cellular phones and digital cameras, also reinforce expectations of fast results that spill over into war, some scholars say. In what's called "the CNN effect," the unblinking eye of video news and unending chatter of the Internet quicken and maybe intensify the public's reaction to the carnage of battle.

"The American people have never been known for their patience, and I suppose with these 24-7 news cycles and access to the Internet, everything seems to have accelerated," says Richard Melanson, who teaches a class on public opinion and foreign policy at the U.S. military's National War College in Washington, D.C.

America's young no longer feel personally threatened, either. The military draft is history. These days, mostly working-class teenagers volunteer to do the fighting.

Charles Moskos, a sociologist at Northwestern University, believes America has lost zeal for warfare because the children of its elite rarely serve. The all-volunteer military is one of many legacies of Vietnam today.

Bobby Blair, a Vietnam veteran from Holliston, Mass., recently spoke about Iraq to a church youth group. "None of them personally know of anyone who's in Iraq," he said. "They didn't realize how serious it was. I said, 'Do you think we're watching a video game?' And some of them said it was almost that."

Greater wealth and smaller families make Americans even more protective of their children and more loath to send them into battle than they once were, some argue. They are "sort of hothouse kids," says Harvey Sapolsky, the retired head of security studies at the Massachusetts Institute of Technology, who notes, "My grandparents had seven kids, my parents had two."