The bombings in Spain now reverberating around the world are raising the specter of a new phenomenon: the possibility of a terror group bringing down a government.
While it is not yet certain that Al Qaeda was behind the attacks - or that the bombings alone were responsible for the fall of the Spanish government - the impact of the strikes nonetheless has affected everything from Wall Street to the political cohesiveness of Western democracies.
This, experts say, is raising the possibility of an emerging new tactic of terror groups worldwide. After Spain, terrorists are likely to draw the conclusion that carefully timed attacks can influence electoral outcomes. To be sure, militant groups throughout history have used bombs and bluster to try to deliver political messages.
But never before, analysts say, has an attack led to the fall of a government. While many factors ultimately lay behind the defeat of retiring Prime Minister José María Aznar's conservative Popular Party in Sunday's election, the Madrid massacre is widely believed to be one of them.
Consequently, the bombings and their aftermath could embolden terror groups in the future. "The attack was obviously an operational success, but it achieved a political outcome too," says Jim Walsh, an international security expert at Harvard University's Kennedy School of Government. "Silvio Berlusconi in Italy, John Howard in Australia, and Tony Blair in England have to be more worried today than they were four days ago."
Like Mr. Aznar, those leaders supported President Bush's war effort in Iraq, without the approval of their electorates. They may fear building pressure for change within because of these attacks.
Yet the bombings could produce the opposite result as well. History suggests that influencing nations through terrorist acts is not a definite science. Examples abound of countries gaining in fortitude in the face of bald strikes: In the US after 9/11, in Italy in the 1970s against the Red Brigade, and more recently in Saudi Arabia, Turkey, and several other countries hit by Al Qaeda groups.
"Rather than bringing us to our knees, we initiated the greatest onslaught on terrorism directed by a nation-state," says Bruce Hoffman, an expert on terror at the RAND Corp. in Washington, of the US's response after Sept. 11.
The European Union, for its part, is setting up an emergency meeting for Friday to deal with the rising terrorist threat, which may leave the Continent more united in its response as well. What those nations' relations will be with Washington, however, remains less certain.
For now, the attacks do carry the thumbprint of Al Qaeda. Tuesday, Spain named five additional Moroccan Muslim militants as suspects in helping plant the bombs. Three others - with known links to Al Qaeda - are in custody.
Osama bin Laden has long targeted Spain. In his 1996 declaration of war against the US, he mentioned reclaiming Andalucia as a goal. That is the name Arabs gave to southern Spain, which was part of the Muslim Empire until 1492. Spain has been mentioned several times since then, including by Mr. bin Laden's No. 2, Ayman al-Zawahiri. Last October, he included it in a list of nations that should be punished for helping the US in Iraq.
"In bin Laden's declaration of war against the US, he talks about Americans being the new crusaders, just like the Spanish," says a senior US government official. "When he alludes to that, Muslims pick up on it - Muslims are so much more cognizant of their history than us. When you talk about the conquest of Spain, it is like yesterday to them."
Intelligence officials do not yet know if the suspects in the Madrid bombings were acting on direct orders from the Al Qaeda leadership, or if they were simply inspired, supported, trained, or funded by the group.
But what's clear is that Al Qaeda is morphing into more of an global movement than a terror group with a simple agenda. In fact, CIA director George Tenet alluded to this in testimony before the Senate Armed Services Committee last week.
"As we continue the battle against Al Qaeda, we must overcome a movement - a global movement infected by Al Qaeda's radical agenda," Mr. Tenet said.
The attacks in Spain bear some other Al Qaeda's hallmarks as well - synchronized explosions that cause massive structural and economic damage, use of cellphones to detonate the explosives, hits planned in another country. But there is also one striking difference: Suicide bombers were not used. That may be part of Al Qaeda's morphing into a movement, or it may be intended to just be deceptive - no one knows for sure.
"I think we're seeing bin Laden make use of talent available to him, even if it doesn't involve suicide," the senior government official says. "There is a whole generation of young Muslims in Europe who admire and support bin Laden, but would rather not die."
Others see even more conscious method in their mayhem. "Al Qaeda is consciously mixing and matching to frustrate our efforts to prevent them from striking," Mr. Hoffman says. "What's worrisome is the ease with which they did this."
Some European countries are clearly worried they may be next. In recent tapes and on websites, Al Qaeda operatives have targeted a number of countries for helping the US.
By one US government official's count, Al Qaeda has now hit 20 of 23 countries that either Zawahiri or bin Laden said they would after the invasion of Afghanistan. "Japan, Norway, and Nigeria are the only ones that haven't been attacked," he says.