Rousting us violently from our false sense of security, the vicious attacks last week in Spain, which killed 200 and wounded 1,500, reminded us that the War on Terror is far from over. In fact, the terrorist cancer isn't only still with us - it's spreading. And Europe is the War on Terror's newest front.

Despite initial beliefs that the bombing was the evil handiwork of the Basque separatist-terrorist group, ETA, it now seems almost certain that the Madrid massacre came at the hands of al Qaeda - or a radical Islamic affiliate.

This is no real surprise: Spain has been in al Qaeda's crosshairs for quite a while. A Spanish restaurant in Morocco was bombed last May, killing 33. (Another bomb exploded near the Spanish consulate.) In fact, last October, Osama bin Laden identified Spain, as well as Japan, Australia, Italy, Britain and Poland as targets on al Qaeda's hit list.

Al Qaeda is no stranger to Spain either. Hijacker Mohammed Atta met with other terrorists there two months before he flew the first plane into the Twin Towers. And since 9/11, the Spanish have arrested a number of important al Qaeda operatives. Sleeper cells probably still exist.

And why not hit Spain? Al Qaeda has often mentioned Andalusia (southern Spain) as the western anchor of its dream pan-Islamic caliphate - a territory stretching from Spain in the West to Indonesia in the East. And Spanish Prime Minister Jose Maria Aznar has been a staunch ally of the U.S. in the War on Terror, deploying 1,300 Spanish troops to Iraq last June.

Other clues pointing to al Qaeda: The killing was indiscriminate; it caused mass casualties; it came without warning, and the bombings were coordinated, multiple (10) and near simultaneous (within 15 minutes) - all al Qaeda trademarks.

But late last week nobody really wanted to believe it was al Qaeda. In fact, there was a palpable resistance to accepting, at a minimum, al Qaeda's complicity in the attacks. Many hoped (silently) that it was a local problem, namely the ETA. Everyone wanted to believe that al Qaeda was a goner and that bin Laden would soon show up on TV news getting his teeth examined by an Army medic on the heels of his capture in some dark, dank Afghan cave.

The news of the spring offensive against al Qaeda and the Taliban along the Pakistan-Afghanistan border brought a genuine sense of euphoria. It seemed the noose around al Qaeda was tightening and soon we could put this baby to bed. Many Americans, ever the eternal optimists, hoped that maybe, just maybe, we were coming to the end of this wrenching chapter in American history.

There was justification to feel this way. Al Qaeda has been on the defensive since 9/11 and it had been 30 months without an attack on U.S. soil. After a spate of attacks overseas last year, al Qaeda had not struck outside of Iraq in almost four months. With the presidential primary season in full swing, attentions turned elsewhere and terrorism as an issue of concern among American voters dropped precipitously in the polls to outside the top ten.

But things look different today as the initial shock of the Madrid attacks wears off and we come around to the sobering reality: The specter of terrorism is still with us. Almost no region of the world can now claim that it's immune to this scourge.

Beware: Al Qaeda rarely makes idle threats. They'll try to strike the other targets on their hit list. And, right here at home, they'll do their best to disrupt our national elections this fall, just like they did in Spain.

We are much safer today than we were on 9/11, but there will be stormy days ahead in the War on Terror. The horrors of 9/11 - and now 3/11 - must steel the international community against the blight of terrorism. It's increasingly clear that no one is ever fully inoculated from this disease.

The bombings in Madrid sadly remind us - and the world - that the War on Terror isn't just about the United States. We must win this campaign and we can by hanging together. But if we don't hang together - al Qaeda will surely try to hang us separately.

Peter Brookes is a senior fellow for National Security Affairs at the Heritage Foundation.