In the wake of the attacks in Spain, Fareed Zakaria reminds us who it is we are fighting ... regardless of whether it was ETA or Al Qaeda that was to blame:

"The purpose of terrorism," Vladimir Lenin once said, "is to terrorize." Like much of what he said, this is wrong. Terrorism has traditionally been used to advance political goals. That's why a rule of terrorists used to be: "We want a few people dead and a lot of people watching." Terrorists sought attention but didn't want people to lose sympathy for their cause.

Yet with many terrorist groups -- like ETA, like al Qaeda -- violence has become an end in itself. They want a lot of people dead, period.