Alva Review-Courier -

PARIS (AP) — From Barcelona to Times Square and beyond, extremists have used vehicles as deadly weapons with alarming frequency in recent years, whether to promote jihad, get attention or express despair.

In response, ugly concrete blocks as well as more aesthetic deterrents are sprouting up in front of landmarks and ordinary public places around the world. Security experts say such barriers would have minimized the fatal damage wreaked on Spain this week — yet warn that as long as motor vehicles exist, some risks will always remain.

While cars and trucks have been used for scattered violence...