President Obama and Attorney General Eric Holder have decided to bring five of those who plotted the 9/11 hijackings to Manhattan to stand trial in federal court.

One of those who will be tried is Khalid Sheikh Mohammed, the principal architect of the 9/11 attacks and someone believed to have been involved in the 1993 World Trade Center bombings, the 2000 aborted plan to attack Los Angeles International Airport and other atrocities. This decision carries the clear message that the War on Terror should never have been considered a real military action against a foreign entity, but a police action not unlike the War on Drugs or against organized crime.

It's a critical difference, and the reframing brings with it potential psychological whiplash in the American people, many of whom will now be left trying to sort out whether they were misled in a dramatic, wholesale fashion by a former President, or by this one. Either conclusion is anxiety-provoking. The decision to try these men in civilian court also, however, has other, very serious psychological implications for many millions of Americans.

First, the families of those killed in the 9/11 attacks will see those who orchestrated the murders of their loved ones lawyered-up, dressed up, with their own supporters potentially in attendance or demonstrating in the streets. Their futures will be determined not by the military form of justice that takes into account the way facts are gathered on a battlefield in times of war, but by whether they were read their Miranda rights prior to being arrested and whether they were treated by the standards extended to American citizens who are arrested for armed robbery or rape.

They will contemplate for months or years the very real possibility that those who destroyed their families will go free on technicalities. Beyond the families of victims, the entire population of Manhattan and the cities immediately surrounding it can be expected to experience symptoms consistent with the reawakening of the terror of September 11. They will see legions of security forces deployed in their streets. They may have a vague or more acute sense that the city is again being attacked-or that it will be attacked during the trials. They may avoid certain areas of the city, or avoid the city entirely-for prolonged periods of time. They may experience low mood, insomnia, flashbacks or nightmares.

Hopefully, the Obama Administration will team up with New York state officials to offer specialized psychological services through schools and churches and synagogues and police departments, in order to stave off some of the inevitable psychological fallout. These services should be deployed soon and should be available for a significant period of time after the trials have concluded. Beyond Manhattan and its neighboring cities, beyond New York State, the nation as a whole will, of course, be in a prolonged state of hypervigilance (another hallmark of posttraumatic stress), wondering whether terrorists will see Manhattan during the 9/11 trials as the target to end all targets, the ultimate canvas for a bloody monument to Jihad.

Forget anything like normal consumer patterns or tourism during the trials. People don't tend to flock to prime targets for dirty bombs. It's going to be ugly psychologically for Americans, even if the 9/11 defendants are ultimately convicted.

If they're found innocent due to violations of their civil rights, something vital in the fabric of the American psyche-the sense that we can protect one another and rely on our government to help us do it-could begin to fray.

Dr. Keith Ablow is a psychiatry correspondent for FOX News Channel and a New York Times bestselling author. His book, "Living the Truth: Transform Your Life through the Power of Insight and Honesty" has launched a new self-help movement including www.livingthetruth.com. Dr. Ablow can be emailed at info@keithablow.com.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team.