WASHINGTON -- New details are coming to light about the suspect in Monday's in Toronto. Alek Minassian posted a cryptic message on Facebook just before the attack, praising an American mass murderer.

Minassian was arrested without incident, after pointing what turned out to be a cellphone at an officer. .

Law enforcement officials have been warning of vehicle attacks for several years. That's why security changes have been made in cities across the U.S. In Washington, D.C., barriers prevent vehicles from jumping the curb into pedestrians. They're strong enough to stop a truck, and most public buildings and many tourist destinations in Washington have them.

The goal is to prevent what happened in Toronto, and a repeat of what happened last October in New York City. On Halloween, in lower Manhattan killing eight people. In the aftermath of that attack, New York City's mayor called for spending $50 million to install 1,500 additional barriers.

In Las Vegas, city leaders have called for the installation of hundreds of additional barriers between the streets and sidewalks along the strip. In Washington, a city that welcomes about 22 million visitors annually, new parking restrictions limit the number of cars on the streets around some major events.

But law enforcement officials will say it also takes a mix of intelligence gathering and public awareness to keep the public safe.