The attacks at the World Trade Center and the Pentagon will forever guide how the country's youngest generation thinks and feels, experts say, much as World War II and the Vietnam War marked the generations before them.

These young Americans barely remember the space shuttle Challenger explosion in 1986. A suspect was apprehended too quickly for the Oklahoma City bombing in 1995 to threaten their sense of security. The 1999 killings at Columbine High School were significant, but not of the magnitude that would shape the mentality of an entire age generation.

Their defining moment is now.

``There are thousands of people dead, and we will face a mass outpouring of grief which will permanently be embedded in young people's brains the way I, at age 3, remember clearly the assassination of President JFK," said Marian Salzman, a strategist in the New York office of Euro RSCG, a marketing agency. "It taught me that death is real, and it's forever. For today's young people, this is that and much, much more."

These youngest Americans, born since 1977 and commonly called Generation Y or Echo Boomers, number about 71 million.

``This is Generation Y's moment," said Ann Fishman, who tracks generational trends and runs the Generational Targeted Marketing firm in New Orleans. "It will change them for now and forever."

Fishman predicted that the generation would react in the self-assured, civic-minded way that characterizes it.

``This generation feels empowered, not only to have successful lives but also to help people," she said. "They'll want to go out and get this settled."

Joel Englestein, a junior at George Washington University in Washington, had retaliation on his mind after Tuesday's attack.

``When I first saw the World Trade Center collapse, I was like, `Send out the war planes out right now!"' said Englestein, 20, of Denville, N.J. "But now I want to know exactly who did this. I just don't want more innocent people to die."

Adrian Ferguson, 17, a senior at Hayfield Secondary School in Alexandria, Va., also was pondering the U.S. government's response against the terrorists.

``My generation is going to be affected by this. It's a new type of warfare and it's going to be more dangerous in the future," he said.

In fact, Robert L. Moore, anthropology professor at Rollins College in Winter Park, Fla., said the tragedy's aftermath will have greater power in molding the generation than the terrorist acts themselves.

``This will be a trigger, but what will really define this generation is how our leaders will respond," Moore said.

Meanwhile, young people are realizing their safety is at risk.

``I thought that America was so much more secure than this," said Tanya Ortiz, 22, a pre-med student at George Washington University. "America is not as powerful as we thought."

Richard Braungart, a professor of sociology, political science and international relations at Syracuse University, discussed the attacks with his freshman citizenship students and said it would take time for them to grasp their significance, given that they have no intimacy with war.

Evan Colton, 17, a senior at Washington International School in Washington, is trying to figure out the meaning of the violence.

``Certainly there hasn't been anything comparable to this in our lives," he said. "Just about every generation has had a major war, from World War II to Vietnam. We got away with not having to deal with one, but a major war may come out of this."

Vanessa Adrien, 20, a New York University student from Falls Church, Va., lives within earshot of the sirens going off since the first plane crashed into the World Trade Center. She used to see the Twin Towers from her balcony.

``This has been the worst attack on the U.S. since Pearl Harbor, and that event alone, for our generation, was something very distant and historic; it was nothing close enough for us to fully grasp," she said.

Experts say this generation will likely be on guard, less trusting.

``From now on, because their history cannot change, Generation Y will come up with an attitude that will define them," Fishman said. "Political correctness is probably out the window. They are going to be suspicious, and who can blame them, when terrorism hit them in their young faces?"
(Michele M. Melendez can be contacted at michele.melendez@newhouse.com; Jose Alfredo Flores can be contacted at jose.flores@newhouse.com)