Once again, we find ourselves asking the familiar question: How can we prevent terrorist attacks such as that in New York City on Tuesday?

We can’t — at least not without infringing upon liberties we Americans cherish.

In mid-afternoon Tuesday, Sayfullo Saipov, 29, who came to this country from Uzbekistan in 2010, used a rented truck to mow down pedestrians and bicyclists. At least eight died. Another 11 were injured. The assault ended only when the truck was disabled by crashing into a school bus.

Police shot the driver when he emerged, brandishing a BB gun and a paintball gun and yelling “Allahu Akbar!”

Obviously, Saipov is a sick and deranged person. By the definitions of most human beings, anyone who would murder innocent people at random, solely for the pleasure of killing, is mentally ill.

Killers like Saipov are pushed into it by Islamic terrorist groups. They are credited with sophisticated use of psychology to create “lone wolf” murderers throughout the world.

It is impossible to prevent someone determined to kill from doing so. Do we ban rental trucks? Kitchen knives? Pressure cookers and household chemicals?

It can’t be done.

The only way to stop the carnage is to find and eliminate the brainwashers who use the internet to create murderers.

One analyst, commenting hours after the attack Tuesday, suggested, “We have to defeat the ideology.” He is correct, but only to an extent.

The analyst talked of defeating terrorism as a creed. But so crazed with power are Islamic extremist leaders that they will be defeated only when they are destroyed.

A brutal prescription? No more so than what they have in mind for us.