If you know where to look, it’s easy to find evidence of Spain’s Islamic past: You can see it in Spanish architecture and in the faces of the people. You can hear it in Spanish music, especially flamenco, and in the Spanish language itself.

Despite these undeniable historical links between Spain and the Islamic world, Spaniards have no interest in turning back the clock, not after their ancestors spent seven centuries expelling the Muslim invaders who forced themselves on Spain. However, there is one group that remains committed to such a “reunion”: Islamist radicals.

A few weeks ago, the FBI arrested eight men in charge of plotting to blow up the underground rail tunnels that link New Jersey and New York. The suspects included members of al-Qaeda living both in and outside of the United States.

An overlooked detail in the story was the name of one of the alleged masterminds of the plot: “Emir Andalusi.” As with many terrorists, that’s not his real name but, instead, what the French call a nom de guerre, a war-time alias. And as with most such aliases, it provides an insight into his and other jihadist motivations and aspirations.

“Andalusi” comes from “Al Andalus,” the Arabic name for southern Spain, the part known as Andalusia today. As one Israeli writer has pointed out, references to “old Muslim Spain are . . . [increasingly] common among jihadists who have set themselves against the Western world.”

The best-known such reference is Osama bin Laden’s 2001 video message that declared that al-Qaeda would not permit the repeat of “the tragedy of Andalusia” in Palestine. The “tragedy” he was referring to was the expulsion of the Muslim invaders by Spanish Christian forces.

In case the Western world didn’t get the point, al-Zawahiri, al-Qaeda’s number two, “later swore that ‘the tragedy of Al Andalus’ must not be repeated.”

It isn’t just al-Qaeda that wants to force this. Hamas isn’t just interested in Israel. It has “demanded the return of the city of Seville to Islam” and what it calls “the lost paradise of Al Andalus.”

These dreams of “Al Andalus” make Spain a target as the Spanish have already learned the hard way. And Spain isn’t a target because of its policies toward the United States or the Middle East, but because its existence is regarded as a “tragedy” by the jihadists. As former Spanish Prime Minister Aznar put it, the problem with al-Qaeda has been 1,300 years in the making.

Unfortunately, the current Spanish Prime Minister, Zapatero, seems to share the same sense of denial that the British elites do as described in Melanie Phillips’s book Londonistan, which I have talked about on “BreakPoint.” He has demonstrated open contempt for Spain’s Catholic heritage while increasingly accommodating Islamic interests. Some five hundred years after the fall of the last Islamic stronghold in Spain, his government is financing the teaching of Islam in public schools.

What’s it going to take for the West to wake up? There is a real clash of worldviews, and it’s deadly. And just like between the two great World Wars, Europe is asleep.